Dr Chong
庄博士
Good afternoon, everyone. Congratulations on making it this far in the course. Today is our last lecture of the semester. This week and next week will be dedicated to presentations. You’ll have the option to record videos with your group mates during the lecture slot or another available slot.
大家下午好。恭喜您已完成本课程的学习。今天是我们这个学期的最后一堂课。本周和下周将专门进行演示。您可以选择在讲座时段或其他可用时段与小组成员一起录制视频。
This Thursday is a public holiday, and Friday is also a university holiday, so you’ll have a long weekend. Take this time to enjoy the break—maybe spend some time in nature or take a few days away from studies and work.
这周四是公共假期，周五也是大学假期，所以你将度过一个长周末。花点时间享受休息——也许花一些时间在大自然中，或者从学习和工作中抽出几天时间。
[Test]
[测试]
In week 13, we’ll have our second test. The details are available on Canvas, but I’ll summarize them here. On Monday of week 13, we’ll use the same lecture slot for Test Two. The format will be similar to Test One, with a start time of 12:30pm, so if you need time to get something to eat before the test, you can. For now, we’re planning for one and a half hours. I’m aiming to set a one-hour paper, but if it turns out you need more time after I finalize the questions, we can adjust accordingly. The test venue will be here as well. Content will cover from lecture 3 up to today’s lecture, so everything except lectures one and two will be included. The format and rules are the same as Test One, so it will be a closed-book exam with secure internet, just like before. There will also be an attachment included in the exam, don’t forget about that.
第 13 周，我们将进行第二次测试。详细信息可在 Canvas 上找到，但我将在这里进行总结。第 13 周的星期一，我们将使用相同的讲座时段进行测试二。形式与测试一类似，开始时间为中午12:30 ，因此如果您在测试前需要时间吃点东西，也可以。目前，我们计划一个半小时。我的目标是设定一个小时的论文，但如果我完成问题后发现你需要更多时间，我们可以相应调整。测试场地也将在这里。内容涵盖从第三讲到今天的讲座，因此除了第一讲和第二讲之外的所有内容都将包括在内。格式和规则与测试一相同，因此这将是一场闭卷考试，有安全的互联网，就像以前一样。考试中还会包含一个附件，不要忘记。
In week 12, I’ll open a few consultation slots. If you’d like a consultation, you can come by my office, or we can arrange a time. Feel free to come with friends if that helps. I’ll provide more details on this later this week or early next week.
第 12 周，我将开设一些咨询时段。如果您想咨询，可以来我的办公室，或者我们可以安排时间。如果有帮助，请随时与朋友一起来。我将在本周晚些时候或下周初提供更多详细信息。
As mentioned earlier, all this information can also be found on Canvas. Like Test One, I noticed some feedback from the mid-course evaluations, specifically comments about the ten questions being largely application-based. This aligns with something in pedagogy known as Bloom's Taxonomy. In terms of cognitive processing, the higher the level, the more critical thinking is involved, which is beneficial for learning. For the group project, you're actually working at the highest level – creating, by synthesizing what you've learned and researched.
如前所述，所有这些信息也可以在 Canvas 上找到。与测试一一样，我注意到中期评估中的一些反馈，特别是关于主要基于应用程序的十个问题的评论。这与教育学中称为布鲁姆分类法的东西是一致的。在认知加工方面，水平越高，涉及的批判性思维就越多，这对学习是有利的。对于小组项目，你实际上是在最高水平上工作——通过综合你所学到和研究的知识来创造。
For the test, we’re likely to focus on the application level since this is difficult to test at the "create" level. Our learning objectives target understanding, applying, analyzing, and evaluating. The test format will be similar to Test One, focusing mainly on application, with some recall of foundational concepts as well. The goal is to see how well you understand and apply the concepts. Another point that came up in discussions is the challenge of not having past-year questions for practice.
对于测试，我们可能会关注应用程序级别，因为这很难在“创建”级别进行测试。我们的学习目标是理解、应用、分析和评估。测试形式与测试一类似，主要侧重于应用，也会回忆一些基本概念。目的是看看您对这些概念的理解和应用程度。讨论中提出的另一点是没有过去一年的练习题的挑战。
[PeerWise]
[同行]
To address this, I'm introducing a collaborative approach to creating practice questions. We’ll be using a platform called PeerWise, which allows the entire class to crowdsource multiple-choice practice questions. With 106 students, if each of you creates one question, you’ll collectively generate 106 questions. It’s a valuable way to gather practice material before Test Two.
为了解决这个问题，我引入了一种协作方法来创建练习题。我们将使用一个名为PeerWise的平台，该平台允许全班众包多项选择练习题。有 106 名学生，如果每个人都创建一个问题，那么总共会生成 106 个问题。这是在测试二之前收集练习材料的一种很有价值的方法。
To get started, you’ll need to join the CM5241 PeerWise group, where you can learn how to create effective questions. There are handouts and workshops available to guide you through the process, including a video on designing quality questions. In previous semesters, this was done as a group assignment, but since we already have a group project, each person will only need to create one question this time. When you create questions, consider providing a clear rationale and solution explanation. This will help your classmates understand the reasoning behind each question. Once you join, you’ll see examples from previous semesters, along with student ratings and solution explanations. You can add attachments or screenshots for detailed solutions, making it a valuable resource for the whole class. You’ll find all the necessary information to get started on the PeerWise page. The handout and a self-paced workshop will guide you through the platform. Now, before we begin today’s session, let’s start with a quick summary of last week’s material.
首先，您需要加入 CM5241 PeerWise小组，在这里您可以学习如何创建有效的问题。有讲义和研讨会可指导您完成整个过程，包括有关设计质量问题的视频。在之前的学期中，这是作为小组作业完成的，但由于我们已经有一个小组项目，所以这次每个人只需要创建一个问题。当您创建问题时，请考虑提供清晰的理由和解决方案说明。这将帮助您的同学理解每个问题背后的推理。加入后，您将看到前几个学期的示例，以及学生评分和解决方案说明。您可以添加附件或屏幕截图来获取详细的解决方案，使其成为全班的宝贵资源。您将在PeerWise页面上找到开始使用所需的所有信息。讲义和自定进度的研讨会将引导您使用该平台。现在，在开始今天的会议之前，让我们先快速总结一下上周的材料。
By Thursday, there should be approximately 106 questions available for you to practice. This schedule should allow ample time over the long weekend to relax and then return to tackle the questions afterward. If anyone submits questions earlier, those can be tried out before Thursday. Once live, you’ll be able to explore and answer these questions and give ratings or constructive feedback. Your ratings can reflect the quality of each question, with options for both positive feedback and improvement suggestions. All contributions will be anonymous from a student perspective, although I will be able to see the questions and comments. I may select particularly creative or well-constructed questions from the pool to include in future tests.
到周四，应该会有大约 106 个问题可供您练习。这个时间表应该让长周末有足够的时间放松，然后再回来解决问题。如果有人提前提交问题，可以在周四之前试用。一旦上线，您将能够探索和回答这些问题并给出评分或建设性反馈。您的评分可以反映每个问题的质量，并提供积极反馈和改进建议的选项。从学生的角度来看，所有贡献都是匿名的，尽管我将能够看到问题和评论。我可能会从池中选择特别有创意或结构良好的问题以包含在未来的测试中。
[TeamMates]
[队友]
For group feedback and peer evaluations, later today you should receive an email inviting you to a feedback system where each group member will assign points to their peers. Each group of four people will have 40 points to distribute. If everyone contributed equally, you might assign 10 points per person. If someone contributed notably more, you can assign them a higher score, with other scores adjusted to reflect the balance. The scoring will be anonymous for students, so individuals won't know who assigned them a particular score, although I’ll be able to see it. This feedback won’t impact your final grades unless there are significant concerns, such as comments from multiple group members indicating an unequal contribution. Otherwise, all group members will receive the same grade for the presentation or video, with adjustments made only in rare cases.
对于小组反馈和同行评估，今天晚些时候您应该会收到一封电子邮件，邀请您进入反馈系统，每个小组成员将在该系统中为其同行分配分数。每组四人将分配 40 积分。如果每个人的贡献均等，您可以为每人分配 10 分。如果某人贡献显着更多，您可以为他们分配更高的分数，并调整其他分数以反映平衡。评分对学生来说是匿名的，因此个人不会知道谁给他们分配了特定的分数，尽管我可以看到它。此反馈不会影响您的最终成绩，除非存在重大问题，例如多个小组成员的评论表明贡献不平等。否则，所有小组成员的演示或视频都会获得相同的评分，仅在极少数情况下才会进行调整。
Let’s aim for a positive and constructive collaboration!
让我们致力于积极、建设性的合作！
[Kahoot]
[卡胡特]
When ions hit a continuous-dynode electron multiplier, what will be emitted from the dynode surface?
当离子撞击连续打拿极电子倍增器时，打拿极表面会发射什么？
The answer here is secondary electrons, not backscatter electrons. This can happen when ion beams or primary electrons hit the surface, and what comes off from that impact are the secondary electrons. In contrast, photoelectrons are emitted when light shines on a metal surface with enough energy to overcome the metal's work function, leading to electrons leaving the surface—this is known as the photoelectric effect, a principle described by Einstein.
这里的答案是二次电子，而不是反向散射电子。当离子束或初级电子撞击表面时，就会发生这种情况，而撞击产生的就是次级电子。相比之下，当光以足够的能量照射金属表面以克服金属的功函数时，就会发射光电子，导致电子离开表面——这就是所谓的光电效应，这是爱因斯坦描述的原理。
Both backscatter and secondary electrons are commonly used in scanning electron microscopy (SEM) for imaging purposes. For the question here, the answer is secondary electrons.
反向散射和二次电子通常用于扫描电子显微镜 (SEM) 中进行成像。对于这里的问题，答案是二次电子。
In EI, molecules lose electrons by which of the following mechanisms?
在 EI 中，分子通过以下哪种机制失去电子？
The mechanism involves electrostatic repulsion. When electrons collide with molecules, this electrostatic repulsion leads to the ejection of electrons from those molecules. This mechanism is covered in the slides. In contrast, for chemical ionization, electrons interact with a reagent gas molecule first, which then collides and reacts to ionize the analyte of interest. So, in this case, the answer would be electrostatic repulsion.
该机制涉及静电排斥。当电子与分子碰撞时，这种静电排斥导致电子从这些分子中喷射出来。幻灯片中介绍了该机制。相比之下，对于化学电离，电子首先与反应气体分子相互作用，然后碰撞并反应以电离感兴趣的分析物。因此，在这种情况下，答案是静电排斥。
Which ion source may NOT be suitable for identifying the molecular mass of analyte?
哪种离子源可能不适合鉴定分析物的分子质量？
The answer is EI because we’re looking for the molecular mass of the analyte, and EI is known for being a hard ionization method. This means it imparts a lot of energy on the analyte, causing extensive fragmentation. As a result, you may not be able to see the molecular ion peak clearly with EI, unlike with softer ionization methods like chemical ionization (CI), electrospray ionization (ESI), or MALDI, which tend to preserve the molecular ion.
答案是 EI，因为我们正在寻找分析物的分子质量，而 EI 因是一种硬电离方法而闻名。这意味着它向分析物传递大量能量，导致广泛的碎片。因此，您可能无法使用 EI 清楚地看到分子离子峰，这与化学电离 (CI)、电喷雾电离 (ESI) 或 MALDI 等较软的电离方法不同，这些方法往往会保留分子离子。
EI has a lower ionization efficiency than that of CI. True or false?
EI 的电离效率比 CI 低。是真是假？
The answer is true. The reason is that EI involves direct electron bombardment in a high-vacuum system, where ionization efficiency is relatively low. In contrast, CI uses a reagent gas under a slightly lower vacuum, typically around 100 pascals, where electrons first ionize the reagent gas, and the reagent gas in its ionized form then collides with the analyte, increasing the probability of ionization compared to EI.
答案是正确的。原因是 EI 涉及高真空系统中的直接电子轰击，电离效率相对较低。相比之下，CI 使用真空度稍低（通常约为 100 帕斯卡）的反应气，其中电子首先电离反应气，然后电离形式的反应气与分析物碰撞，与 EI 相比，增加了电离的可能性。
Which ion source does NOT involve the use of reagent gas?
哪种离子源不涉及使用反应气？
Unlike CI, ESI doesn’t use a reagent gas. ESI operates on a different principle.
与CI 不同，ESI 不使用反应气。 ESI 的运作原理不同。
In ESI, when a charged droplet reaches its Rayleigh limit, it will undergo ___.
在 ESI中，当带电液滴达到其瑞利极限时，它将经历 ___。
Here, charged droplets are generated, and as a counterflow of drying gas evaporates the solvent, the droplets decrease in size, reaching a point where Coulombic explosion occurs due to surface tension no longer being able to contain the charged droplet. This mechanism leads to the droplets breaking up until ions are ejected. Unlike Rayleigh scattering or charge recombination, which don't apply here, this process focuses on charge separation as the droplet size decreases.
在这里，产生带电液滴，随着干燥气体的逆流蒸发溶剂，液滴尺寸减小，达到由于表面张力不再能够容纳带电液滴而发生库仑爆炸的点。这种机制导致液滴破裂，直到离子被喷射出来。与此处不适用的瑞利散射或电荷复合不同，该过程侧重于随着液滴尺寸减小而发生电荷分离。
Rayleigh scattering is used to explain why the sky appears blue. When the sun is high (e.g., around noon), sunlight travels a shorter path through the atmosphere. Because blue light has a shorter wavelength, it scatters more effectively than red light, resulting in the sky’s blue colour. At sunrise or sunset, however, sunlight must travel a longer path through the atmosphere, scattering out most of the blue light, leaving primarily the red hues to reach us, which creates the golden colours of dawn and dusk. A simple demo to illustrate this effect can be done using milk in water, which represents atmospheric particles: when light shines through, the side closest to the light source appears blue, while the opposite side looks reddish.
瑞利散射用于解释为什么天空呈现蓝色。当太阳很高时（例如，中午左右），阳光穿过大气层的路径较短。由于蓝光的波长较短，因此它比红光更有效地散射，从而导致天空呈现蓝色。然而，在日出或日落时，阳光必须在大气中传播更长的路径，散射掉大部分蓝光，主要留下红色色调到达我们，从而产生黎明和黄昏的金色。可以使用水中的牛奶来完成一个简单的演示来说明这种效果，它代表大气粒子：当光线穿过时，最靠近光源的一侧呈现蓝色，而相对的一侧看起来呈红色。
In MALDI, the laser irradiation is mainly absorbed by ___.
在MALDI中，激光照射主要被___吸收。
It's important to understand that the matrix, not the analyte, is responsible for absorbing the laser radiation. Different matrices are used based on the type of analyte to absorb specific wavelengths of laser light. The absorbed energy is then transferred to the analyte, causing it to desorb and ionize.
重要的是要了解基质而不是分析物负责吸收激光辐射。根据分析物的类型使用不同的基质来吸收特定波长的激光。然后吸收的能量转移到分析物，导致其解吸和电离。
In EI, KE of singly charged ions is mainly dependent on ___, before entering the mass analyser.
在 EI 中，单电荷离子的 KE 在进入质量分析器之前主要取决于 ___。
Accelerating voltage comes into play in the ion source, particularly before ions enter the mass spectrometer, where they are accelerated through plates using this voltage. The energy each ion gains during acceleration is governed by the accelerating voltage, which we previously calculated using a specific equation.
加速电压在离子源中发挥作用，特别是在离子进入质谱仪之前，离子在质谱仪中使用该电压通过板加速。每个离子在加速过程中获得的能量由加速电压控制，我们之前使用特定方程计算了该电压。
Which component of a mass spectrometer primarily determines its resolution?
质谱仪的哪个组件主要决定其分辨率？
Mass resolution in a mass spectrometer is determined by the mass analyzer, which separates ions based on their mass-to-charge ratio (m/z). The resolution of the mass spectrometer is crucial because it affects how distinctly the ions can be separated and identified.
质谱仪中的质量分辨率由质量分析器确定，质量分析器根据离子的质荷比 (m/z) 来分离离子。质谱仪的分辨率至关重要，因为它影响离子分离和识别的清晰度。
[Continuation of Lecture]
【讲座继续】
We’ll start with the concept of the magnetic sector analyzer, which is a high-resolution tool, albeit with a large setup. During a recent lab tour, you might have seen one on the bench—it’s quite large, so bringing it into a lecture wasn’t feasible.
我们将从扇形磁分析仪的概念开始，它是一种高分辨率工具，尽管设置很大。在最近的一次实验室参观中，您可能在长凳上看到过一个——它相当大，因此将其带入讲座中是不可行的。
The analyzer functions by directing ions through a magnetic field, the core component of the setup, which can utilize either a permanent magnet or an electromagnet. The latter is more common in modern instruments, as it allows adjustment of the magnetic field by modifying the voltage or current input, offering more flexibility than a permanent magnet. The purpose of this magnetic field is to direct the ion beam along a circular path. One specific setup angle, for instance, is 90 degrees.
该分析仪通过引导离子穿过磁场来发挥作用，磁场是该装置的核心组件，可以利用永磁体或电磁体。后者在现代仪器中更常见，因为它允许通过修改电压或电流输入来调整磁场，比永磁体提供更大的灵活性。该磁场的目的是沿着圆形路径引导离子束。例如，一种特定的设置角度是 90 度。
With the ion source set up, typically using electron ionization (EI) to create ions, these ions then pass through a pair of slits, “A” and “B,” and accelerating plates that deliver kinetic energy based on the voltage applied. The assumption is often made that ions will pass through the slit with uniform kinetic energy; however, this is not strictly accurate since ions might have different kinetic energies before even reaching the slit, which could result in a small distribution of kinetic energy values.
设置离子源后，通常使用电子电离 (EI) 来产生离子，这些离子然后穿过一对狭缝“ A ”和“B”以及加速板，加速板根据所施加的电压传递动能。通常假设离子将以均匀的动能穿过狭缝；然而，这并不严格准确，因为离子在到达狭缝之前可能具有不同的动能，这可能导致动能值的分布较小。
Understanding the interaction of forces within the magnetic sector is crucial. The inward magnetic force (FM) balances the outward centrifugal force (FC) to keep ions traveling in a circular path. Think of holding a spinning object, with centrifugal force pulling it outward while magnetic force pulls it inward. When these two forces equalize, the ion moves circularly. For clarity, we know the formulas governing these forces, so balancing them lets us rearrange the equations to find the velocity of the ion, which depends on the magnetic field strength (B), the ion’s charge (z), and the electronic charge (e).
了解磁区内力的相互作用至关重要。向内的磁力 (FM) 平衡向外的离心力 (FC)，以保持离子沿圆形路径行进。想象一下握住一个旋转的物体，离心力将其向外拉，而磁力将其向内拉。当这两个力平衡时，离子会做圆周运动。为了清楚起见，我们知道控制这些力的公式，因此平衡它们可以让我们重新排列方程以找到离子的速度，该速度取决于磁场强度 (B)、离子的电荷 (z) 和电子电荷( e ）。
We start by manipulating the initial equation by rearranging terms. By substituting and rearranging terms, we reach an expression where most variables cancel out, isolating the mass-to-charge ratio (m/z) in terms of the square of the magnetic field strength, radius, and applied voltage.
我们首先通过重新排列项来操纵初始方程。通过替换和重新排列项，我们得到了一个大多数变量相互抵消的表达式，以磁场强度、半径和施加电压的平方来分离质荷比 (m/z)。
The equation shows that m/z is proportional to the square of both the magnetic field strength and radius while being inversely proportional to the accelerating voltage. Importantly, this tells us that ions can be separated based on their mass-to-charge ratio by changing the magnetic field strength (B) or the accelerating voltage (V).
该方程表明，m/z 与磁场强度和半径的平方成正比，与加速电压成反比。重要的是，这告诉我们，通过改变磁场强度 (B) 或加速电压 (V)，可以根据离子的质荷比来分离离子。
Older machines, which used a permanent magnet, also allowed adjustments in the radius (r) from the center, but this was less convenient than adjusting the magnetic field strength with an electromagnet. In modern instruments, B and V are typically adjusted, making separation easier and more practical.
使用永磁体的旧机器也允许调整距中心的半径 (r)，但这不如使用电磁体调整磁场强度方便。在现代仪器中，通常会调整 B 和 V，使分离更容易、更实用。
The ions pass through a magnetic field, which deflects them based on their mass-to-charge ratio. Heavier ions experience less deflection and are neutralized if they touch the magnet, while lighter ions, being deflected more significantly, may also be filtered out if they don’t fit the path. This setup essentially serves as a mass filter, only allowing ions with a specific mass-to-charge ratio to reach the detector, or ion transducer, based on the selected variables.
离子穿过磁场，磁场根据离子的质荷比使其偏转。较重的离子会经历较小的偏转，如果它们接触磁铁，就会被中和，而较轻的离子会发生更明显的偏转，如果它们不适合路径，也可能会被过滤掉。该设置本质上用作质量过滤器，根据所选变量仅允许具有特定质荷比的离子到达检测器或离子传感器。
This method allows the magnetic sector analyzer to act as a precise mass filter with high resolution compared to other mass analyzers, effectively isolating ions of specific mass-to-charge ratios by manipulating the magnetic field strength and accelerating voltage.
与其他质量分析器相比，该方法允许扇形磁分析器充当具有高分辨率的精确质量过滤器，通过操纵磁场强度和加速电压来有效地隔离特定质荷比的离子。
Let's revisit the concept of kinetic energy distribution as ions pass through the slit. Although we initially assume they have the same kinetic energy at this point, in reality, minor differences in kinetic energy exist due to their distribution prior to entering the slit. This variation can impact the resolution and sensitivity of the mass analyzer. To address this, we employ a double focusing mass analyzer, which incorporates both an electrostatic analyzer and a magnetic sector.
让我们重新审视离子通过狭缝时动能分布的概念。尽管我们最初假设它们此时具有相同的动能，但实际上，由于它们在进入狭缝之前的分布，动能存在微小差异。这种变化会影响质量分析仪的分辨率和灵敏度。为了解决这个问题，我们采用了双聚焦质量分析仪，其中包含静电分析仪和磁扇区。
In this setup, the ions are first accelerated through the accelerating plates before entering the electrostatic analyzer. This component filters ions based on their kinetic energy, allowing only a narrow band of ions with specific energy levels to pass through. Following this, the magnetic sector operates similarly to a traditional magnetic sector analyzer, where the ions are deflected based on their mass-to-charge ratios. Heavier ions are deflected less and are detected later, while lighter ions experience more significant deflection.
在此设置中，离子在进入静电分析仪之前首先通过加速板加速。该组件根据离子的动能过滤离子，只允许具有特定能级的窄带离子通过。此后，磁区的运行方式与传统磁区分析仪类似，离子根据其质荷比进行偏转。较重的离子偏转较少并且较晚被检测到，而较轻的离子则经历更显着的偏转。
The ions that successfully navigate both the electrostatic and magnetic analyses reach an array transducer capable of capturing ions with varying mass-to-charge ratios simultaneously. This process is analogous to the functioning of a photodiode array detector, where multiple mass-to-charge ratios can be analyzed at once.
成功通过静电和磁分析的离子到达能够同时捕获具有不同质荷比的离子的阵列传感器。这个过程类似于光电二极管阵列探测器的功能，可以同时分析多个质荷比。
The double focusing mass analyzer effectively enhances sensitivity and resolution by utilizing both types of analyzers. Additionally, there are variations in design for double focusing mass analyzers, but their fundamental purpose remains the same: to focus the ion beam onto a specific point, ensuring that both the kinetic energy and mass-to-charge ratios are finely tuned for accurate detection.
双聚焦质量分析器通过利用两种类型的分析器，有效地提高了灵敏度和分辨率。此外，双聚焦质量分析仪的设计有所不同，但其基本目的仍然相同：将离子束聚焦到特定点，确保动能和质荷比均经过微调，以实现精确检测。
[Break]
[休息]
With that in mind, it might be a good time for a brief five-minute break before we resume and continue discussing the topic, as the upcoming material may require additional focus and attention.
考虑到这一点，在我们继续讨论该主题之前，可能是短暂休息五分钟的好时机，因为即将发布的材料可能需要额外的关注和关注。
In PowerPoint, you can enhance your presentations by using 3D images and animations effectively. For example, you can insert a 3D object directly into your slide, or if you have your own three-dimensional objects, you can customize them further. The process for adding animations is straightforward. Most of the animations I use in my presentations stem from the built-in features in PowerPoint, specifically the "Morph" transition. This transition allows me to rearrange elements smoothly from one slide to another, making the presentation flow better.
在 PowerPoint 中，您可以通过有效地使用 3D 图像和动画来增强演示文稿。例如，您可以将 3D 对象直接插入幻灯片中，或者如果您有自己的三维对象，则可以进一步自定义它们。添加动画的过程很简单。我在演示文稿中使用的大多数动画都源自 PowerPoint 中的内置功能，特别是“变形”过渡。这种过渡使我能够顺利地将元素从一张幻灯片重新排列到另一张幻灯片，从而使演示文稿更加流畅。
When using PowerPoint, you can select icons and other elements directly from the platform. For instance, if I want to utilize a specific icon, I can easily copy and paste it onto the slide. Additionally, I can customize elements, like changing the color of an object or rearranging components, to enhance visual appeal.
使用 PowerPoint 时，您可以直接从平台选择图标和其他元素。例如，如果我想使用特定图标，我可以轻松地将其复制并粘贴到幻灯片上。此外，我可以自定义元素，例如更改对象的颜色或重新排列组件，以增强视觉吸引力。
By applying the "Morph" transition, when you click to advance the slide, the objects animate into their new positions seamlessly, creating a dynamic visual effect. This feature is particularly useful for illustrating complex processes or concepts, such as biological pathways, by allowing for smooth transitions between different stages or components.
通过应用“变形”过渡，当您单击以推进幻灯片时，对象会无缝地动画到新位置，从而创建动态视觉效果。通过允许不同阶段或组件之间的平滑过渡，此功能对于说明复杂的过程或概念（例如生物途径）特别有用。
Overall, utilizing the "Morph" transition and other animation tools in PowerPoint can significantly elevate the quality of your presentations. Once you become familiar with these features, you'll find that incorporating them is quite simple and can greatly enhance audience engagement.
总体而言，利用 PowerPoint 中的“Morph”过渡和其他动画工具可以显着提高演示文稿的质量。一旦您熟悉了这些功能，您就会发现将它们合并起来非常简单，并且可以极大地提高观众的参与度。
[Lecture Resumes]
【讲座继续】
Now, let’s turn our attention to one of the most widely used mass analyzers, the quadrupole mass analyzer. The quadrupole consists of four rods arranged in parallel, creating a space through which ions must pass to reach the detector. This analyzer acts as a mass filter, allowing only ions with a specific mass-to-charge ratio to pass through based on the application of alternating current (AC) and direct current (DC) voltages.
现在，让我们将注意力转向最广泛使用的质量分析器之一：四极杆质量分析器。四极杆由四个平行排列的杆组成，形成一个空间，离子必须通过该空间才能到达检测器。该分析仪充当质量过滤器，基于交流 (AC) 和直流 (DC) 电压的应用，仅允许具有特定质荷比的离子通过。
To understand how it operates, we can visualize the quadrupole setup along three axes: the Z-axis, X-axis, and Y-axis. The DC voltage, which is direct current, is applied to the rods in a specific arrangement—two rods receive positive voltage while the other two are negative, creating an electric field. Alongside this, a radio frequency AC voltage is superimposed. This setup can be a bit confusing, but essentially, it creates a dynamic field that changes the stability of ions as they travel through.
为了了解其工作原理，我们可以沿三个轴可视化四极杆设置：Z 轴、X 轴和 Y 轴。直流电压（即直流电）以特定的排列方式施加到杆上——两个杆接收正电压，而另外两个杆接收负电压，从而产生电场。除此之外，还会叠加射频交流电压。这种设置可能有点令人困惑，但本质上，它创建了一个动态场，改变了离子穿过时的稳定性。
As ions enter the quadrupole, they are influenced by both the AC and DC voltages. By adjusting these voltages, we can create conditions where only ions with a particular mass-to-charge ratio are stable enough to pass through the quadrupole and reach the detector. Ions that do not meet the criteria will collide with the rods and become neutralized, preventing their detection.
当离子进入四极杆时，它们会受到交流和直流电压的影响。通过调整这些电压，我们可以创造条件，只有具有特定质荷比的离子足够稳定，可以通过四极杆并到达检测器。不符合标准的离子将与棒碰撞并被中和，从而阻止其检测。
The analogy of AC and DC voltages can be likened to an ambiguous relationship; the AC voltage oscillates, representing the push and pull in a relationship, while the DC voltage provides a steady influence, much like consistent communication in a partnership. When ions make contact with the rods, it's akin to them touching a solid object—they lose their charge and cannot proceed any further, illustrating the delicate balance of the quadrupole system.
交流和直流电压的类比可以比喻为一种模糊的关系；交流电压会振荡，代表关系中的推力和拉力，而直流电压则提供稳定的影响，就像伙伴关系中的一致沟通一样。当离子与杆接触时，就像它们接触固体一样——它们失去电荷并且不能继续前进，这说明了四极系统的微妙平衡。
To gain a better understanding of the workings of the quadrupole mass analyzer, it's essential to explore the concepts of AC and DC voltages in greater detail, as these are crucial to its operation.
为了更好地了解四极杆质量分析器的工作原理，有必要更详细地探讨交流和直流电压的概念，因为这些对其操作至关重要。
For example, consider a laptop charger that specifies it requires an input of between 100 to 240 volts and 1.5 amps of alternating current (AC), represented by a particular symbol. This charger converts the AC input to provide an output of approximately 19.5 volts and 3.33 amps of direct current (DC), which is indicated by a different symbol. AC and DC represent two different types of electricity.
例如，考虑一个笔记本电脑充电器，指定它需要 100 至 240 伏和 1.5 安培的交流电 (AC) 输入，由特定符号表示。该充电器将交流输入转换为提供约 19.5 伏和 3.33 安培的直流 (DC) 输出，由不同的符号表示。交流和直流代表两种不同类型的电力。
In your home, electrical outlets deliver AC. The flow of electrons in AC does not follow a continuous loop; instead, it oscillates back and forth, similar to the ebb and flow of ocean tides. In contrast, electronic devices such as laptops and mobile phones operate on DC electricity, where electrons flow in a single direction—from one terminal to another—akin to water flowing downstream in a river.
在您的家中，电源插座提供交流电。交流电中的电子流动并不遵循连续循环；相反，它来回振荡，类似于海洋潮汐的涨落。相比之下，笔记本电脑和移动电话等电子设备依靠直流电运行，电子沿单一方向流动（从一个终端流向另一个终端），类似于河流中的水向下游流动。
AC is primarily used to transport electricity from power stations to urban areas because it can easily be transformed to higher or lower voltages using transformers, making it efficient for long-distance transmission. Although there are some high-voltage DC transmission lines, we won’t delve into those details. DC, or direct current, is more commonly used in the circuit boards of smaller electronic devices, as it allows for greater control and enables the construction of smaller, more compact circuits.
交流电主要用于将电力从发电站输送到城市地区，因为它可以很容易地使用变压器转换为更高或更低的电压，从而可以有效地进行长距离传输。虽然有一些高压直流输电线路，但我们不会深入研究那些细节。 DC（即直流电）更常用于较小电子设备的电路板，因为它可以实现更好的控制并能够构建更小、更紧凑的电路。
Many appliances actually utilize a combination of AC and DC. For instance, a washing machine may use AC to power the induction motor that spins the drum but relies on DC to operate the control circuitry, which manages the settings, lights, timers, and motor speed.
许多电器实际上结合使用了交流电和直流电。例如，洗衣机可以使用交流电为旋转滚筒的感应电机供电，但依靠直流电来操作控制电路，控制电路管理设置、灯光、计时器和电机速度。
To convert AC to DC, a rectifier is employed, a device commonly found in electronics. Conversely, an inverter is used to transform DC back to AC; this is often seen in solar power systems. We've discussed power inverters in detail in previous materials, so be sure to check those out for more information.
为了将交流电转换为直流电，需要使用整流器，这是电子设备中常见的设备。相反，逆变器用于将直流电变回交流电；这在太阳能发电系统中很常见。我们在之前的材料中详细讨论了电源逆变器，因此请务必查看这些材料以获取更多信息。
In summary, this video offers insight into the differences between AC and DC electricity. Direct current is similar to the concept of using a battery, while alternating current operates differently.
总之，该视频深入了解了交流电和直流电之间的差异。直流电与使用电池的概念类似，而交流电的工作原理则不同。
In discussing the application of AC (alternating current) and DC (direct current) in a quadrupole mass analyzer, we can break down how these currents interact with ions in the device. When we talk about AC voltage, it alternates between positive and negative directions, which means it switches back and forth continuously. In contrast, direct current maintains a constant flow in one direction.
在讨论 AC（交流电）和 DC（直流电）在四极杆质量分析器中的应用时，我们可以分解这些电流如何与设备中的离子相互作用。当我们谈论交流电压时，它在正方向和负方向之间交替，这意味着它会不断地来回切换。相反，直流电在一个方向上保持恒定流动。
For the quadrupole setup, each pair of electrodes experiences either positive or negative DC voltage, and an AC voltage is superimposed on this. When we consider the situation without the DC voltage, applying just the AC creates a scenario where positively charged ions, represented by a purple line, are influenced by the positive AC current across the electrodes. In this case, the positively charged ions are repelled from the positive electrodes, effectively pushing them toward the center of the quadrupole. This can be visualized as trying to escape someone chasing you, where you instinctively move towards the middle to evade them.
对于四极设置，每对电极都会经历正或负直流电压，并在其上叠加交流电压。当我们考虑没有直流电压的情况时，仅施加交流电压会产生一种情况，其中带正电的离子（由紫色线表示）受到电极上的正交流电流的影响。在这种情况下，带正电的离子被正极排斥，有效地将它们推向四极的中心。这可以想象为试图逃避追赶你的人，你本能地向中间移动以躲避他们。
Now, when we introduce negative DC voltage, the negatively charged electrodes attract the ions toward them. The movement of ions depends on the polarity of the voltage: during positive AC cycles, ions move toward the center, while during negative AC cycles, they are drawn towards the electrodes.
现在，当我们引入负直流电压时，带负电的电极会将离子吸引向它们。离子的运动取决于电压的极性：在正交流循环期间，离子向中心移动，而在负交流循环期间，它们被吸引向电极。
As we alternate between positive and negative voltage, ions experience a wavy movement, accelerating from the ion source to the detector (transducer). For ions under positive DC conditions, larger ions with higher mass-to-charge ratios have greater momentum, making them less influenced by the AC field. Therefore, larger ions tend to pass through more easily because they are less affected by the AC oscillations compared to smaller ions, which experience greater amplitude shifts in response to the AC field.
当我们在正电压和负电压之间交替时，离子会经历波状运动，从离子源加速到检测器（传感器）。对于正直流条件下的离子，具有较高质荷比的较大离子具有较大的动量，使得它们受交流场的影响较小。因此，较大的离子往往更容易通过，因为与较小的离子相比，它们受交流振荡的影响较小，较小的离子响应交流场而经历更大的振幅变化。
Conversely, when considering negative DC voltage, the same principles apply, but the dynamics change. The negative DC attracts the ions toward the electrodes. Larger ions, while still possessing greater momentum, are now directed toward the electrodes, gaining momentum and more likely to collide with them. This interaction can neutralize the ions, causing them to lose their charge and momentum, ultimately preventing them from reaching the transducer.
相反，当考虑负直流电压时，适用相同的原理，但动态会发生变化。负直流电将离子吸引向电极。较大的离子虽然仍然拥有更大的动量，但现在被引导向电极，获得动量并且更有可能与电极碰撞。这种相互作用可以中和离子，导致它们失去电荷和动量，最终阻止它们到达传感器。
The interplay of AC and DC in a quadrupole mass analyzer effectively sorts ions based on their mass-to-charge ratios. The AC voltage facilitates movement and separation, while the DC voltage dictates the attraction or repulsion of the ions toward the electrodes, allowing for precise control over which ions can pass through to the detector.
四极质量分析仪中交流和直流的相互作用可根据离子的质荷比对离子进行有效分类。交流电压有利于移动和分离，而直流电压则决定离子对电极的吸引力或排斥力，从而可以精确控制哪些离子可以通过到达检测器。
It's essential to understand how AC (alternating current) and DC (direct current) interact with ions to facilitate mass filtering. The AC serves both positive and negative cycles, but the behavior of ions changes significantly when DC is applied.
了解 AC（交流电）和 DC（直流电）如何与离子相互作用以促进质量过滤至关重要。交流电可用于正循环和负循环，但当施加直流电时，离子的行为会发生显着变化。
When negative DC current is applied, ions are drawn more strongly towards the electrodes due to the gain in momentum. Initially, without the DC voltage, the K ions within the electric field would behave uniformly. When negative DC is present, the ions are attracted towards both ends of the quadrupole, leading to their eventual contact with the electrodes, where they can be neutralized and lost from the system.
当施加负直流电流时，由于动量的增加，离子被更强烈地吸引向电极。最初，如果没有直流电压，电场内的 K 离子将表现均匀。当存在负直流时，离子被吸引向四极杆的两端，导致它们最终与电极接触，在那里它们可以被中和并从系统中消失。
In this system, when a positive DC voltage is applied, it favors the passage of ions with a larger mass-to-charge ratio. These heavier ions tend to remain centered in the channel due to their greater momentum, making it more difficult for them to be deflected by the electric fields. Conversely, under negative DC conditions, the larger ions are more likely to be neutralized when they collide with the electrodes, as their increased momentum drives them toward the electrodes, allowing ions with a smaller mass-to-charge ratio to pass through instead.
在该系统中，当施加正直流电压时，有利于质荷比较大的离子通过。这些较重的离子由于动量较大而倾向于保持在通道的中心，这使得它们更难以被电场偏转。相反，在负直流条件下，较大的离子在与电极碰撞时更有可能被中和，因为它们增加的动量将它们推向电极，从而允许质荷比较小的离子通过。
Visualizing the AC component, during the positive half-cycle, ions converge toward the center along the z-axis, as positively charged ions repel each other. In the negative half-cycle, the ions diverge toward the electrodes, creating a wavy movement. When AC is applied without DC, ions can strike the electrodes and become neutralized.
可视化交流分量，在正半周期期间，离子沿 z 轴向中心汇聚，因为带正电的离子相互排斥。在负半周期中，离子向电极发散，产生波状运动。当施加交流电而没有直流电时，离子会撞击电极并被中和。
Introducing the positive DC voltage along with the AC alters the dynamics significantly. The momentum of ions can be represented by the equation p=mv (momentum equals mass times velocity). Rearranging this to express momentum in terms of energy allows us to derive that momentum is proportional to the square root of the mass of the ion. This indicates that heavier ions experience more difficulty in being deflected compared to lighter ions. Therefore, in this configuration, heavier ions tend to remain closer to the center channel.
引入正直流电压和交流电压会显着改变动态。离子的动量可以用方程 p=mv 表示（动量等于质量乘以速度）。重新排列它以用能量来表达动量，我们可以得出动量与离子质量的平方根成正比。这表明与较轻的离子相比，较重的离子更难以偏转。因此，在这种配置中，较重的离子往往更靠近中心通道。
The design of the quadrupole creates distinct filtering effects based on the applied voltages. The positive DC voltage paired with AC allows for the passage of heavier ions, while the negative DC voltage facilitates the passage of lighter ions. The two configurations create a high-pass filter (for larger mass-to-charge ratios) and a low-pass filter (for smaller mass-to-charge ratios).
四极杆的设计根据施加的电压产生不同的滤波效果。正直流电压与交流电配对允许较重的离子通过，而负直流电压则有利于较轻的离子通过。这两种配置创建一个高通滤波器（用于较大的质荷比）和一个低通滤波器（用于较小的质荷比）。
When the two systems overlap, they create a unique mass filtering mechanism, allowing only a narrow range of ions with specific mass-to-charge ratios to pass through at any given time. By adjusting the voltages of the DC and AC currents, it is possible to selectively filter ions of varying masses. Typically, higher voltages correspond to the passage of ions with higher mass-to-charge ratios. This scanning capability allows the quadrupole mass filter to be an effective tool in mass spectrometry, enabling detailed analysis of complex mixtures based on their mass characteristics.
当两个系统重叠时，它们会产生独特的质量过滤机制，在任何给定时间只允许具有特定质荷比的狭窄范围的离子通过。通过调节直流和交流电流的电压，可以选择性地过滤不同质量的离子。通常，较高的电压对应于具有较高质荷比的离子的通过。这种扫描功能使四极杆滤质器成为质谱分析中的有效工具，能够根据复杂混合物的质量特性对其进行详细分析。
The workings of mass analyzers in the electric field can indeed be complex, and while delving into the mathematical aspects can be insightful, visual demonstrations often provide a clearer understanding. The quadrupole mass analyzer is also commonly used in gas chromatography-mass spectrometry (GC-MS) systems.
电场中质量分析仪的工作确实很复杂，虽然深入研究数学方面可能会很有洞察力，但视觉演示通常可以提供更清晰的理解。四极杆质量分析器也常用于气相色谱-质谱 (GC-MS) 系统。
The quadrupole mass analyzer has several advantages. It is compact and relatively lightweight, making it practical for various applications. Its cost-effectiveness and high scanning rate—capable of scanning an entire mass spectrum in just 100 milliseconds—are significant benefits. However, it does come with limitations; notably, its resolution is lower than some other mass analyzers, typically around 1000. Nevertheless, for many applications that don't require ultra-high resolution, a quadrupole is an excellent choice.
四极杆质量分析器有几个优点。它结构紧凑且相对轻便，适用于各种应用。其成本效益和高扫描速率（能够在短短 100 毫秒内扫描整个质谱）是显着的优势。然而，它确实有局限性；值得注意的是，它的分辨率低于其他一些质量分析仪，通常在 1000 左右。尽管如此，对于许多不需要超高分辨率的应用来说，四极杆是一个很好的选择。
Moving on to the next analyzer, the Time-of-Flight (TOF) mass analyzer, you may find it helpful to compare its principles to those of the quadrupole. TOF analyzers also feature an ionization region and an accelerating region, similar to those in Electron Ionization (EI). The key principle here involves the kinetic energy gained by the ions during acceleration, which can be calculated using specific equations.
转到下一个分析仪，即飞行时间 (TOF) 质量分析仪，您可能会发现将其原理与四极杆的原理进行比较很有帮助。 TOF分析仪还具有电离区域和加速区域，类似于电子电离 (EI) 中的区域。这里的关键原理涉及离子在加速过程中获得的动能，可以使用特定的方程进行计算。
In a TOF setup, ions of varying mass-to-charge ratios are accelerated. According to the equation governing kinetic energy, lighter ions will generally travel faster than heavier ions when subjected to the same electric field. This characteristic allows TOF analyzers to separate ions based on their speeds as they move through the flight tube.
在 TOF 设置中，不同质荷比的离子会被加速。根据控制动能的方程，当受到相同的电场时，较轻的离子通常比较重的离子移动得更快。这一特性使得 TOF分析仪能够根据离子在飞行管中移动时的速度来分离离子。
Understanding these principles and how different mass analyzers operate can enhance your grasp of their applications in analytical chemistry and help you communicate these concepts more effectively during your presentations.
了解这些原理以及不同质量分析仪的工作原理可以增强您对其在分析化学中的应用的掌握，并帮助您在演示过程中更有效地传达这些概念。
Okay, let's take a look at the response. Eventually, the class chose "faster" as the answer, and most of the class got it right. So, why is that? For ions with a smaller mass-to-charge ratio, the lower the mass, the higher the velocity when they have the same, or about the same, kinetic energy. This kinetic energy will remain constant. In other words, when you have a smaller mass, the velocity will increase. Therefore, ions with the same kinetic energy entering the system will travel faster.
好的，我们来看看回复。最终，全班同学选择了“更快”作为答案，大多数同学都答对了。那么，这是为什么呢？对于质荷比较小的离子，质量越低，当它们具有相同或大致相同的动能时，速度越高。该动能将保持恒定。换句话说，当质量较小时，速度会增加。因此，具有相同动能的离子进入系统时会运动得更快。
If the length of the tube is L, we can calculate the velocity from the equation provided. We can also calculate the flight time of the analyte, or ions, when they reach the ion detector or ion transistor. The faster the ions travel, the shorter the flight time. Typically, for time-of-flight (TOF) analyzers, the flight time is about 1 to 50 microseconds, which is quite fast.
如果管的长度为 L，我们可以根据提供的方程计算速度。我们还可以计算分析物或离子到达离子检测器或离子晶体管时的飞行时间。离子行进越快，飞行时间越短。通常，对于飞行时间 (TOF)分析仪来说，飞行时间约为 1 至 50 微秒，这是相当快的。
There are typically two different types of TOF analyzers: linear and reflectron. In the linear TOF analyzer, the resolution depends on the length of the tube—the longer the tube, the higher the resolution. This is because we can separate ions better based on their velocity differences.
TOF分析仪通常有两种不同类型：线性分析仪和反射分析仪。在线性TOF分析仪中，分辨率取决于管的长度——管越长，分辨率越高。这是因为我们可以根据离子的速度差异更好地分离离子。
Similar to Electron Ionization (EI), the ionization part can utilize secondary electrons or laser-generated photons. Secondary ions can also be used, similar to the gradient gas employed. This energy can ionize the sample, and then the electric field can accelerate the ions.
与电子电离 (EI) 类似，电离部分可以利用二次电子或激光产生的光子。类似于所使用的梯度气体，也可以使用二次离子。该能量可以使样品电离，然后电场可以加速离子。
The typical accelerating voltage is between 1,000 to 10,000 volts. The speed, or velocity, will depend on the kinetic energy and the mass of the ions. This ability to separate ions is based on their mass-to-charge ratio in the TOF mass analyzer.
典型的加速电压在 1,000 至 10,000 伏之间。速度取决于离子的动能和质量。这种分离离子的能力是基于 TOF 质量分析器中离子的质荷比。
However, TOF analyzers typically have relatively low resolution. This is because the resolution depends on the length of the drift tube, the spatial distribution, and the velocity distribution.
然而，TOF分析仪通常具有相对较低的分辨率。这是因为分辨率取决于漂移管的长度、空间分布和速度分布。
In a double focusing mass analyzer, we address the distribution of kinetic energy before the ions enter the drift tube. This distribution is not like that in a double focusing system because it doesn't narrow down certain velocities before acceleration. A lack of double focusing can lead to issues, as there is a distribution of velocities even before acceleration.
在双聚焦质量分析仪中，我们解决了离子进入漂移管之前的动能分布问题。这种分布与双聚焦系统中的分布不同，因为它不会在加速之前缩小某些速度。缺乏双聚焦可能会导致问题，因为甚至在加速之前就存在速度分布。
In double focusing mass analyzers, an electrostatic analyzer narrows down the energy. Before the ions are accelerated, they have a certain form of kinetic energy. Let's denote this as KE, while the kinetic energy due to the applied accelerating voltage is KE’. The velocity of the ions depends on this kinetic energy, but the KE value may not solely come from the applied voltage; it can also include energy that the ions had prior to acceleration. This can also affect the resolution.
在双聚焦质量分析仪中，静电分析仪缩小了能量范围。在离子被加速之前，它们具有一定形式的动能。我们将其表示为 KE ，而由于施加的加速电压而产生的动能是 KE 。离子的速度取决于该动能，但 KE 值可能不仅仅来自施加的电压；它还可以包括离子在加速之前所具有的能量。这也会影响分辨率。
So, how do we solve this?
那么，我们如何解决这个问题呢？
This can be solved using an orthogonal acceleration time-of-flight (TOF) mass analyzer. Instead of using a linear one, the orthogonal one has a specific cell, so it doesn't need to reflect. This is an ion mirror. The ions are accelerated through this tube, which is the first flight tube. If they have a higher kinetic energy, imagine that this is a mirror. So you have a light that bounces through it. However, this is not a physical mirror; it compensates for the different kinetic energy. When you have a higher kinetic energy, you can penetrate deeper before being reflected in that direction.
这可以使用正交加速飞行时间 (TOF) 质量分析仪来解决。正交的不是使用线性的，而是具有特定的单元格，因此不需要反射。这是离子镜。离子通过该管加速，该管是第一个飞行管。如果它们有更高的动能，想象这是一面镜子。所以你就有了一个可以反射的光。然而，这不是一面物理镜子；而是一面镜子。它补偿了不同的动能。当你拥有更高的动能时，你可以穿透得更深，然后再被反射到那个方向。
For example, let's say the red color represents ions with higher kinetic energy; they will penetrate deeper. In contrast, the blue color represents ions with lower kinetic energy, and they will not penetrate as deeply.
例如，假设红色代表具有较高动能的离子；他们会渗透得更深。相反，蓝色代表动能较低的离子，它们不会渗透得那么深。
Imagine that inside, one ion has like a corner, where the faster ion will penetrate further due to larger momentum. So they can actually penetrate deeper. It's not very good to draw this, but let's say this is the reflector. A faster ion traveling from here will travel deeper; the faster ion will travel deeper into the reflector because it has higher momentum. When it turns a corner, it's harder for it to turn than for a slower ion with lower kinetic energy.
想象一下，在内部，一个离子就像一个角，由于动量较大，速度较快的离子将穿透得更远。所以他们实际上可以渗透得更深。画这个不太好，但我们假设这是反射器。从这里出发的较快的离子将行进得更深；更快的离子将进入反射器更深处，因为它具有更高的动量。当它转弯时，它比动能较低的较慢离子更难转弯。
So at a certain point, when they reflect back, they will meet each other, meaning those with the same mass-to-charge ratio but different kinetic energy will interact with this reflection. The higher kinetic energy ions will turn deeper before being reflected, while the lower kinetic energy ions will penetrate not as deeply. After passing through the reflector, they will have the same trajectory. Thus, the faster ion will travel deeper into the reflector, while the slower ion will travel less deep. When they accelerate from the same speed, from that point onward, they will reach the detector at about the same time.
因此，在某一时刻，当它们反射回来时，它们会彼此相遇，这意味着那些具有相同质荷比但不同动能的物质将与这种反射相互作用。较高动能的离子在被反射之前会变得更深，而较低动能的离子将穿透得不那么深。经过反射镜后，它们将具有相同的轨迹。因此，较快的离子将行进到反射器的更深处，而较慢的离子将行进得较浅。当它们以相同的速度加速时，从该点开始，它们将大约在同一时间到达探测器。
The advantage of using TOF analyzers lies in their straightforward setup and the accessibility of ion sources, allowing the use of different types of ionization methods. Depending on the length of the flight tube, it can accommodate a virtually unlimited mass range. However, the form factor remains crucial, with typical limitations being around one to two meters. Nonetheless, this design has limited resolution and accessibility, making it less widely used compared to other mass analyzers.
使用 TOF分析仪的优点在于其简单的设置和离子源的可访问性，允许使用不同类型的电离方法。根据飞行管的长度，它可以容纳几乎无限的质量范围。然而，外形尺寸仍然至关重要，典型限制约为一到两米。尽管如此，这种设计的分辨率和可访问性有限，与其他质量分析仪相比，其应用范围较小。
In essence, this reflection helps solve the issue of ions with the same mass-to-charge ratio having different kinetic energies. This concept is similar to the double focusing part, but it operates differently.
本质上，这种反射有助于解决相同质荷比的离子具有不同动能的问题。这个概念与双聚焦部分类似，但操作方式不同。
For me, this analogy helps a bit. The picture might be a bit misleading; the higher kinetic energy ion will travel faster and reach the detector sooner. The orthogonal acceleration TOF analyzer is better because it accounts for differences in kinetic energy, whereas the linear one does not. Thus, it should have a higher resolution compared to the linear one.
对我来说，这个类比有点帮助。图片可能有点误导；动能较高的离子将移动得更快并更快到达检测器。正交加速 TOF分析仪更好，因为它考虑了动能的差异，而线性分析仪则不然。因此，与线性分辨率相比，它应该具有更高的分辨率。
Another advantage of using this design is that it has a longer flight path. Since it isn't linear, in a smaller form factor, it can achieve a longer flight path than a linear design. A linear one typically measures one to two meters, but because of this design, even with a smaller form factor, a longer flight path is possible. A longer flight path translates to better resolution.
使用这种设计的另一个优点是它具有更长的飞行路径。由于它不是线性的，因此在较小的外形尺寸中，它可以实现比线性设计更长的飞行路径。线性飞行器的尺寸通常为一到两米，但由于这种设计，即使外形较小，也可以实现更长的飞行路径。更长的飞行路径意味着更好的分辨率。
Because of this reflection mechanism, different kinetic energies will arrive at the detector simultaneously. In other words, this design has better resolution and sensitivity. Typically, TOF analyzers use microchannel plate electron multipliers. The typical flight time is about nanoseconds to microseconds, which is faster compared to the linear one that has about one to 50 microseconds. This means that the data acquisition unit, which includes the electronics and computer, must process a single pass rapidly for it to be captured effectively.
由于这种反射机制，不同的动能将同时到达探测器。换句话说，这种设计具有更好的分辨率和灵敏度。通常，TOF分析仪使用微通道板电子倍增器。典型的飞行时间约为纳秒到微秒，这比大约 1 到 50 微秒的线性飞行时间要快。这意味着包括电子设备和计算机的数据采集单元必须快速处理单次通过才能有效捕获。
To illustrate, imagine light bouncing off a mirror. In this analogy, consider the ions as different colors of light. The red ions represent those with higher kinetic energy, which will penetrate deeper into the mirror's reflection area, taking a longer path. Conversely, the blue ions, with lower kinetic energy, will not penetrate as deeply.
为了说明这一点，想象一下光从镜子反射回来。在这个类比中，将离子视为不同颜色的光。红色离子代表动能较高的离子，它们会更深地渗透到镜子的反射区域，走更长的路径。相反，动能较低的蓝色离子不会渗透得那么深。
Visualize this scenario like cars navigating a corner. A faster car (higher kinetic energy) will be able to navigate the corner more aggressively, penetrating deeper. In contrast, a slower car (lower kinetic energy) can take the corner more gradually, but it won't go as far into the turn.
想象一下这个场景就像汽车在拐角处行驶一样。速度更快的汽车（动能更高）将能够更积极地过弯，穿透得更深。相比之下，速度较慢的汽车（动能较低）可以更缓慢地过弯，但不会在转弯时走得那么远。
When these ions reach the reflection area, they will meet at the same point despite their initial differences in kinetic energy. Ions with the same mass-to-charge ratio but differing kinetic energies will reflect differently. The higher kinetic energy ions will travel further before being reflected, while the lower kinetic energy ions will reflect sooner.
当这些离子到达反射区域时，尽管它们最初的动能不同，但它们将在同一点相遇。质荷比相同但动能不同的离子会产生不同的反射。较高动能的离子在被反射之前将行进更远，而较低动能的离子将反射得更快。
After passing through the reflector, ions of the same mass-to-charge ratio will have the same trajectory. Thus, the faster ions that penetrated deeper will not have an advantage in reaching the detector. All ions, regardless of their initial kinetic energy, will reach the detector at approximately the same time.
质荷比相同的离子通过反射镜后，将具有相同的轨迹。因此，穿透较深的较快离子在到达检测器时将不具有优势。所有离子，无论其初始动能如何，都会大约在同一时间到达检测器。
In comparing linear TOF analyzers to orthogonal acceleration TOF analyzers, the latter is superior because it accounts for differences in kinetic energy, which the linear version does not. As a result, the orthogonal acceleration analyzer should provide a higher resolution.
在将线性 TOF分析仪与正交加速 TOF分析仪进行比较时，后者更为优越，因为它考虑了动能的差异，而线性版本则没有。因此，正交加速度分析仪应提供更高的分辨率。
It's important to note that data acquisition in this context means that the unit, including the electronics and computer, must process data from a single pass to capture information effectively. The advantage of using TOF analyzers lies in their simplicity of setup and high accessibility of ion sources, as they can accommodate different types of ionization methods, including electron ionization (EI) and chemical ionization (CI). Depending on the flight tube's length, TOF analyzers can theoretically handle a virtually unlimited mass range.
值得注意的是，在这种情况下的数据采集意味着包括电子设备和计算机在内的设备必须处理单次传递的数据才能有效地捕获信息。使用 TOF分析仪的优点在于其设置简单且离子源易于访问，因为它们可以适应不同类型的电离方法，包括电子电离 (EI) 和化学电离 (CI)。根据飞行管的长度，TOF分析仪理论上可以处理几乎无限的质量范围。
However, it’s worth mentioning that the orthogonal acceleration TOF analyzers have certain limitations, such as lower resolution compared to some other mass spectrometers. Additionally, their accessibility is limited, making them less widely used than sector mass analyzers.
然而，值得一提的是，正交加速 TOF分析仪具有一定的局限性，例如与其他一些质谱仪相比分辨率较低。此外，它们的可访问性有限，使得它们不如扇形质量分析仪广泛使用。
So now, how's your mental well-being? This Friday marks the NUS Well-Being Day, so take a break from your studies and research. Use this time to relax and unwind. Since Thursday is a holiday, you have a long weekend ahead—Thursday, Friday, and Saturday—so consider going somewhere enjoyable or simply taking a moment for yourself.
那么现在，您的心理健康状况如何？本周五是新加坡国立大学健康日，所以请暂时停止学习和研究。利用这段时间放松身心。由于星期四是假期，您将有一个长周末（星期四、星期五和星期六），因此请考虑去一个有趣的地方或只是给自己一点时间。
[Break]
[休息]
Let’s do a one-minute meditation. It’s simple but important. Follow along with this guided meditation to help reset your mind. Take a moment to notice how your body expands as you breathe in, and feel it soften as you breathe out. Focus on the gentle rise and fall of your breath, noticing the sensations throughout your body. There’s nothing else to do right now, just allow yourself to be present. When you're ready, you can gently return to your day. Hopefully, this meditation helps you reset. It's especially useful in stressful situations—when you need to take a step back. Even a simple one-minute breathing exercise, or even just 10 to 30 seconds of mindful breathing, can make a difference. It can help calm your nerves before presentations or any significant performance coming up.
让我们进行一分钟的冥想。这很简单但很重要。遵循这个引导冥想可以帮助你重新调整心态。花点时间注意吸气时身体如何扩张，呼气时感觉身体柔软。专注于呼吸的轻微起伏，注意全身的感觉。现在没什么可做的，只要让自己在场即可。准备好后，您就可以轻松地回到一天的生活了。希望这个冥想能帮助你重置。它在压力大的情况下特别有用——当你需要退后一步时。即使是简单的一分钟呼吸练习，或者只是 10 到 30 秒的正念呼吸，也能产生效果。它可以帮助您在演讲或任何重要表演之前平静下来。
[Lecture Resumes]
【讲座继续】
Let's revisit the last two mass analyzers, focusing on the ion trap mass analyzer. It looks something like this from the side, featuring a filament at one end and a ring electrode, which resembles a donut. Surrounding this ring electrode are two end caps, effectively enclosing the ion trap area.
让我们回顾一下最后两台质量分析器，重点关注离子阱质量分析器。从侧面看，它看起来像这样，一端有一根灯丝，还有一个环形电极，类似于甜甜圈。该环形电极周围有两个端盖，有效封闭了离子阱区域。
In this configuration, the ring electrode acts as the central feature of the ion trap. Ions are trapped within this donut-shaped structure before being directed to the electron multiplier transducer.
在此配置中，环形电极充当离子阱的中心特征。离子在被引导至电子倍增器换能器之前被捕获在该环形结构内。
Now, let’s take a closer look at how the ion trap analyser works. Typically, ions are formed and confined for a specific period by electric and magnetic fields within a designated region. This area is where ions with a particular mass-to-charge ratio are trapped, hence the name "ion traps."
现在，让我们仔细看看离子阱分析仪的工作原理。通常，离子在指定区域内通过电场和磁场形成并限制在特定时期内。该区域是具有特定质荷比的离子被捕获的地方，因此被称为“离子陷阱”。
The ring electrode, which is blue in colour, can have a variable radio frequency (RF) voltage applied to it, while the end cap electrodes are grounded. Ions with a specific mass-to-charge ratio will circulate in a stable orbit within the cavity of the ion trap. To visualize this, you can think of the ring electrode as the Earth, with the ions representing the Moon orbiting around it.
蓝色的环形电极可以施加可变射频 (RF) 电压，而端盖电极则接地。具有特定质荷比的离子将在离子阱腔内的稳定轨道上循环。为了形象化这一点，您可以将环形电极视为地球，离子代表绕其运行的月球。
As you increase the RF voltage, heavier ions stabilize while lighter ions become destabilized. When the RF voltage is raised, lighter ions lose stability and collide with the ring electrodes, where they become neutralized. These neutralized ions are captured and eventually released at a certain time, allowing them to travel toward the detector.
当增加射频电压时，较重的离子会稳定，而较轻的离子会变得不稳定。当射频电压升高时，较轻的离子失去稳定性并与环形电极碰撞，在那里它们被中和。这些中和的离子被捕获并最终在某个时间释放，使它们能够向探测器移动。
In the ion trap mass analyzer, you can introduce ions using a pulse ion laser source, whether through Electron Impact (EI) or Chemical Ionization (CI). This process allows the introduction of ions as bursts, with some ions being trapped while others are directed out, depending on the frequency voltage applied. The voltage influences the electric and magnetic fields within the trap. Essentially, this operates like a mass-selective ejection mechanism, where you sequentially trap ions of specific mass-to-charge ratios based on the radio frequency you apply before allowing them to pass into the ion transducer. This method is crucial for later discussions about the tandem aspect of mass spectrometry.
在离子阱质量分析仪中，您可以使用脉冲离子激光源引入离子，无论是通过电子轰击 (EI) 还是化学电离 (CI)。此过程允许以突发形式引入离子，其中一些离子被捕获，而另一些离子被引导出，具体取决于所施加的频率电压。电压影响陷阱内的电场和磁场。从本质上讲，这就像质量选择喷射机制一样，您可以根据应用的射频顺序捕获特定质荷比的离子，然后再让它们进入离子传感器。这种方法对于后续关于质谱串联方面的讨论至关重要。
Another type of ion trap analyzer is the Orbitrap analyzer, which represents one of the newer mass analyzers available. It gained significant recognition, even winning the Nobel Prize in Physics in 1989. Commercially, it became available around 2005 and is characterized by a compact form factor.
另一种类型的离子阱分析仪是 Orbitrap分析仪，它代表了一种较新的质量分析仪。它获得了广泛的认可，甚至于 1989 年获得了诺贝尔物理学奖。它于 2005 年左右投入商业使用，其特点是外形紧凑。
In the Orbitrap analyzer, there is a central electrode shaped like a spindle, surrounded by outer electrodes, which also have a similar spindle shape. A constant voltage or potential is applied between these electrodes. Due to the variation in distance between the electrodes, the electric field experienced by ions in between changes with position. This means that when you apply a constant potential, the electric field's intensity varies throughout the trap.
在Orbitrap分析仪中，有一个纺锤形的中心电极，周围环绕着同样具有类似纺锤形形状的外部电极。在这些电极之间施加恒定的电压或电势。由于电极之间距离的变化，离子之间所经历的电场随着位置的变化而变化。这意味着当您施加恒定电势时，整个陷阱的电场强度会发生变化。
To determine where the electric field is minimal, you can analyze the Orbitrap's design. The minimum electric field occurs at the center of the Orbitrap, where the electric field is least affected by the distance of the electrodes. In contrast, the electric field is stronger at the ends of the Orbitrap where the electrodes are closer together.
要确定电场最小的位置，您可以分析Orbitrap 的设计。最小电场出现在 Orbitrap 的中心，此处电场受电极距离的影响最小。相比之下，Orbitrap 末端的电场更强，电极距离更近。
As an illustration, I will share a video later to depict this process.
作为说明，我稍后将分享一个视频来描述这个过程。
This ion source demonstrates the full-scale analysis, capable of performing tandem mass spectrometry (MS/MS). It is responsible for filtering different ions. The C trap injects ions into the orbitrap, which initially has a somewhat random path. Over time, ions are separated based on their mass-to-charge ratios into specific circular orbits before proceeding to the transducer.
该离子源演示了全尺寸分析，能够执行串联质谱 (MS/MS)。它负责过滤不同的离子。 C 陷阱将离子注入轨道陷阱，轨道陷阱最初具有一定程度的随机路径。随着时间的推移，离子根据其质荷比被分离到特定的圆形轨道中，然后再进入换能器。
The process involves transforming the acquired information into mass spectra across different modes. After this video, there will be an opportunity to explore various mass spectrometry modes. The video showcases the C trap, which concentrates the ions and subjects them to the orbitrap before analysis.
该过程涉及将获取的信息转换为不同模式的质谱。观看此视频后，您将有机会探索各种质谱模式。该视频展示了 C 陷阱，它会聚集离子并在分析之前将它们置于轨道陷阱中。
This is the full-scale analysis, capable of MSMS and filtering different ions. The C track is responsible for injecting ions into the orbit track. Initially, the path is quite random, but after a while, ions are separated based on the mass-to-charge ratio into a circular orbit, moving into the transducer. This process converts information into mass spectrometry in different modes. After the video, the camera can show the various modes.
这是全面的分析，能够进行 MSMS 并过滤不同的离子。 C轨道负责将离子注入轨道。最初，路径是相当随机的，但过了一会儿，离子根据质荷比被分离成圆形轨道，移动到换能器中。该过程以不同的模式将信息转换为质谱。视频结束后，相机可以显示各种模式。
The C track concentrates ions and subjects them to the orbit track for analysis.
C轨道集中离子并将其置于轨道轨道上进行分析。
A €1 coin is about the size of a 50-cent Singapore coin, illustrating the small form factor of the mass analyzer, which can separate mass-to-charge ratios. This analyzer has a high resolution of about 200,000 and a dynamic range, making it compact and less expensive than larger high-resolution mass analyzers. However, it has limitations, including the ability to hold fewer ions and the need for very low pressure to ensure a large mean free path for orbiting ions.
一枚 1 欧元的硬币大约相当于 50 分新加坡硬币的大小，这说明了质量分析仪的小型化，可以分离质荷比。该分析仪具有约 200,000 的高分辨率和动态范围，使其比大型高分辨率质量分析仪更紧凑且更便宜。然而，它也有局限性，包括容纳较少离子的能力以及需要非常低的压力来确保绕轨道运行的离子有较大的平均自由程。
We are done discussing the ion source mass analyzer and the transducer. We won't go into details about the vacuum systems, which include a mechanical pump and a diffusion pump. When transferring from LC or GC to MS, two steps are needed to move from atmospheric pressure to high vacuum using the mechanical pump first, followed by achieving even lower pressure.
我们已经讨论完离子源质量分析器和传感器。我们不会详细介绍真空系统，其中包括机械泵和扩散泵。从 LC 或 GC 转移到 MS 时，需要两个步骤，首先使用机械泵从大气压转移到高真空，然后达到更低的压力。
Next, we will discuss tandem mass spectrometry, which involves components for mass spec and tandem mass spec. Typically, a soft ionization source and two mass analyzers are needed. The first mass analyzer selects precursor ions while ensuring minimal fragmentation. For example, ions A, B, C, and D can be selected as precursor ions. These ions are then introduced into an interaction cell, where they decompose to produce fragments. The selected fragment from the first mass analyzer is then further analyzed in the interaction cell to gather more information about the compounds.
接下来，我们将讨论串联质谱法，其中涉及质谱和串联质谱的组件。通常，需要一个软电离源和两个质量分析器。第一个质量分析器选择前体离子，同时确保最小的碎片。例如，可以选择离子A、B、C和D作为前体离子。然后这些离子被引入相互作用池，在那里它们分解产生碎片。然后，从第一质量分析器中选择的片段在相互作用单元中进一步分析，以收集有关化合物的更多信息。
In the product ion spectrum, mass analyzer one (MA1) is held constant while mass analyzer two (MA2) is scanned. Conversely, in the precursor ion spectrum, the precursor ion is scanned while MA2 is held constant. For example, if the goal is to detect a specific product, such as a functional group like an i,j group among four species (A, B, C, D), only the two species containing the i,j group would be selected.
在产物离子谱中，质量分析器一 (MA1) 保持恒定，同时扫描质量分析器二 (MA2)。相反，在前体离子谱中，在 MA2 保持恒定的同时扫描前体离子。例如，如果目标是检测特定产品，例如四个物种（A、B、C、D）中的i,j基团等官能团，则仅选择包含i,j基团的两个物种。
In this case, MA2 is set to only detect the i,j group, and MA1 is scanned to pick up all molecular ions. However, only the molecules that contain the specific functional group will be visible in the spectrum. This is known as the precursor ion spectrum.
在这种情况下，MA2 设置为仅检测i,j组，扫描 MA1 以拾取所有分子离子。然而，只有包含特定官能团的分子才会在光谱中可见。这称为前体离子谱。
The focus will be on two types of mass spectrometry (MS) spectra: product ion spectrum and precursor ion spectrum. A common tandem mass spectrometry instrument is the triple quadrupole mass spectrometer, which includes three quadrupoles labeled Q1, Q2, and Q3. The first and third quadrupoles serve as mass analyzers. In contrast, the second quadrupole functions differently, as no direct current (DC) voltage is applied; only alternating current (AC) radio frequency is used.
重点将放在两种类型的质谱 (MS) 谱上：产物离子谱和母离子谱。常见的串联质谱仪器是三重四极杆质谱仪，其包括标记为Q1、Q2和Q3的三个四极杆。第一和第三四极杆用作质量分析器。相比之下，第二个四极杆的功能不同，因为没有施加直流 (DC) 电压；仅使用交流 (AC) 射频。
This setup allows the second quadrupole to act as a collision cell, where molecules collide to gain energy and fragment into smaller pieces. Without the DC voltage, it does not serve as a filter but rather focuses ions into the AC path, increasing the likelihood of collisions, hence the term "collision focusing."
这种设置允许第二个四极杆充当碰撞池，分子碰撞以获得能量并分裂成更小的碎片。如果没有直流电压，它就不能充当过滤器，而是将离子聚焦到交流路径中，增加了碰撞的可能性，因此称为“碰撞聚焦”。
In tandem mass spectrometry, there are two types: tandem in space and tandem in time. The tandem in space spectrometer uses two independent mass analyzers located in different spatial regions. In contrast, the tandem in time spectrometer uses a single mass analyzer for all functions, applying it at different times to collect collisions and analyze mass.
串联质谱有两种类型：空间串联和时间串联。串联空间光谱仪使用位于不同空间区域的两个独立的质量分析器。相比之下，串联时间光谱仪使用单个质量分析器来实现所有功能，在不同时间应用它来收集碰撞并分析质量。
Different combinations of analyzers can be used, such as magnetic sector analyzers and electrostatic sector analyzers. The small quadrupole without the direct current serves as a focusing lens for molecules rather than filtering different mass-to-charge ratios. Lastly, the tandem in time spectrometer forms ions in a specific spatial region and then expels unwanted ions, similar to an ion trap, allowing selected ions to dissociate for further analysis.
可以使用分析仪的不同组合，例如扇形磁分析仪和扇形静电分析仪。没有直流电的小四极杆充当分子的聚焦透镜，而不是过滤不同的质荷比。最后，串联时间光谱仪在特定空间区域形成离子，然后排出不需要的离子，类似于离子阱，使选定的离子解离以进行进一步分析。
The collision, mass analysis, and fragmentation occur within the same space in the mass analyzer, which is referred to as the tandem in time spectrometer. This process can be repeated multiple times, enabling configurations such as MS, MS, MS, and so on.
碰撞、质量分析和碎片发生在质量分析器的同一空间内，称为串联时间谱仪。此过程可以重复多次，从而实现 MS、MS、MS 等配置。
In concluding this section, various aspects have been discussed, including the ion source, mass analyzer, ion transducer, and vacuum system. The choice of these components can depend on the specific challenges faced, the need for a tandem mass spectrometry setup, and budget considerations.
在本节的最后，我们讨论了各个方面，包括离子源、质量分析器、离子传感器和真空系统。这些组件的选择取决于所面临的具体挑战、串联质谱设置的需求以及预算考虑因素。
The discussion has centered around three key questions: critical problem solving, resourcefulness, and communication. Over the past 11 weeks, these elements have been integrated into the test and presentation components of the course.
讨论围绕三个关键问题：解决关键问题、足智多谋和沟通。在过去 11 周中，这些元素已融入课程的测试和演示部分。
As a summary, it is essential to review the key learnings from the lectures, which included analyzing raw samples, calibration methods, and general knowledge about chromatography. It is important to note that the first two lectures were not included in the assessments. From lecture three onward, all content is relevant for testing.
总而言之，有必要回顾一下讲座中学到的关键知识，包括分析原始样品、校准方法和有关色谱的一般知识。值得注意的是，前两堂课不包含在评估中。从第三讲开始，所有内容都与测试相关。
