A comprehensive study on resonant scattering of electrons form atmospheric molecules using a new method

摆线色散装置在电子能谱中已被用于电子束的制备和能量分析。虽然这些设备的分辨率不如其他类型的电子能谱仪，但它们的灵敏度已经达到了极高的水平。获得高分辨率的主要困难可以追溯到与垂直于摆线色散板的电子的输入位置有关的像差。与靠近负极板的类似电子相比，靠近正极板的电子通过交叉场区域的速度更快，因此受到的色散更小。事实上，可以说这些设备是低通滤波器，而不是能量分析仪。第二个问题是，在这些器件中，色散往往很小--这意味着获得的分辨率受到机械约束的限制，例如最小实际狭缝尺寸。我们通过创建一种新的多通道摆线色散Dev…克服了这两个限制再来点冰块。静电反射镜位于摆线散射板的两端，以便电子在离开出射孔径之前可以多次通过该装置反弹。使用一个小的预选器来限制进入多程器件的电子的能量范围。这确保了电子只有在通过一定次数后才会离开设备。施加的电压决定了该通道的数量。我们精心设计了静电反射镜，以便它们能抵消上述像差。光线跟踪计算表明，这种结果是一种在分辨率方面可以与半球分析器相媲美的设备，同时保持了与通常的摆线光谱仪的在线磁配置相关的灵敏度。利用这种新的电子光学装置，我们已经设计并正在建造一台绰号为沙池的新电子能谱仪。这是高像差补偿和高强度光谱仪的缩写。沙池的设计还融入了其他创新功能，包括双差压泵，可提供约100的压差。所有的电源都是由计算机控制的，使用了一种比传统系统便宜得多的新型系统。这是通过模拟电源在软件中浮动的方式来实现的。所有电源均参考接地，因此无需隔离即可使用标准模数转换卡。然后使用高压运算放大器放大这些卡的输出，以提供所需的电压范围。较少

Trochoidal dispersive devices have been used in electron spectroscopy to both prepare and energy analyze electron beams. Fantastic sensitivity has been achieved although the resolution of these devices has not been as good as other types of electron spectrometer. The primary difficulty in obtaining high resolution can be traced to an aberration related to the input position of the electrons perpendicular to the trochoidal dispersing plates. Electrons nearer to the positive plate travel through the cross field region quicker and so suffer less dispersion than similar electrons travelling near the negative plate. Indeed, it could be argued that these devices are low-pass filters, not energy analysers. A second problem is that the dispersion tends to be small in these devices- This means that the resolution obtained is limited by mechanical constraints such as the minimum practical slit size. We have overcome both of these limitations by creating a new multi-pass trochoidal dispersive dev … More ice. Electrostatic mirrors are positioned at either end of the trochoidal dispersing plates so that the electrons can bounce a number of times through the device before leaving the exit aperture. A small pre-selector is used to limit the energy range of electrons entering the multi-pass device. This ensures the electrons only exit the device after a certain number of passes. The voltages applied determine this number of passes. We have carefully designed the electrostatic mirrors so that they act to cancel the aberration described above. Ray-tracing calculations show that this results is a device which should be comparable to hemispherical analysers in terms of resolution whilst retaining the sensitivity associated with the in-line magnetic configuration of usual trochoidal spectrometers. Using this new electron-optical device, we have designed and are in the process of constructing a new electron spectrometer nicknamed SHACHI. This an acronym for Spectrometer with High Aberration Compensation and High Intensity. Other innovative features incorporated into the design of SHACHI, include double differential pumping with gives a pressure differential of about 100. The power supplies are all computer-controlled using a novel system that is much cheaper than traditional systems. This is achieved by emulating the way power supplies float in software. All supplies are referenced to ground so standard analog to digital converter cards can be used without the need for isolation. The output from these cards is then amplified using high voltage operational amplifiers to give the required voltage range. Less