RUI: Laser Photoelectron Beam Sources

本研究的目的是研究基于金属衬底上有机薄膜表面激光产生的光电子的强电子束源的特性。最近的研究表明，在超高真空环境下，激光照射传统的光电阴极可以产生高电流密度和大总电流，有机薄膜也可以作为优秀的光电子源。有机薄膜的优点包括大大降低了真空要求和易于制造。本项目将确定有机薄膜光电子的能量、能量扩散、角发散和视源尺寸。在不同的激光波长和脉冲长度下，将研究发射的时间行为。在宿主中含有活性分子的薄膜，以及多种类型的活性分子，将被评估，以及单一材料的涂层。还将探讨基质效应。将建立一个发射过程的动力学模型来解释时间和光谱特征。提出的研究计划是研究新技术和新材料，特别是非线性有机薄膜，可用于在强激光照射下产生高电流密度的电子束。高亮度的电子束可用于集成电路光刻曝光，用于微探针和电子显微镜等仪器；用于点源x射线的产生，以及大型设备，如加速器和自由电子激光器。激光产生的结果表明，可以很容易地产生千安培电流。该技术可以实现多个发射源的同步发射以及光控光束形状。由于可以实现高电流密度和小光斑尺寸以及极快的光斑偏转，因此这些光束与半导体的相互作用应该可以实现一些非常有用的信号处理和开关应用。

The goal of this research is to investigate the characteristics of intense electron beam sources based on laser-generated photoelectrons at the surface of an organic thin film on a metal substrate. Recent work has demonstrated that high current densities and large total currents can be generated by laser illumination of conventional photocathodes in ultrahigh vacuum environments, and also that organic thin films can serve as excellent photoelectron sources. The advantages of organic films include greatly reduced vacuum requirements and ease of fabrication. This project will determine the energies, energy spreads, angular divergences, and apparent source sizes of photoelectrons from organic-thin films. The temporal behavior of the emission will be investigated with various laser wavelengths and pulse lengths. Films containing active molecules in a host, and more than one type of active molecule, will be evaluated, as well as coatings of a single material. Substrate effects will also be explored. A kinetic model of the emission process will be developed to explain the temporal and spectral characteristics. The proposed research program is an investigation of new techniques and materials, particularly nonlinear organic thin films, which can be used to generate electron beams of high current density under intense illumination by a laser. Electron beams of high brightness can be used for integrated circuit lithographic exposure, for instruments such as microprobes and electron microscopes; for point- source X-ray generation, and for large scale devices such as accelerators and free electron lasers. Laser-generated results indicate that kiloampere currents can be produced easily. Synchronized emission from multiple emitters as well as optically controlled beam shapes are possible with this technique. Because high current densities and small spot sizes with extremely rapid spot deflection can be achieved, the interaction of these beams with semiconductors should make possible some very useful signal processing and switching applications.