Development of Angle-Resolved Electron-Stimulated Desorption Spectrometer and its Application to be Detection of Excited Species on Surfaces

我们研制了一种新型的离子谱仪--飞行时间傅里叶变换离子谱仪（TOFFTIS），它在很低的能量下具有很高的探测效率和能量分辨率。TOFFTIS已安装在超高真空兼容的双轴旋转组件上，并安装在超高真空室中。作为初步的实验，我们成功地获得了O^+和CO^+的电子激发解吸，证明了TOFFTIS具有预期的性能.利用TOFFTIS作为一种高效的离子检测器，我们发展了一种新的实验技术，称为角分辨电子激发解吸光谱（ARESDS），用于研究激发态物种在固体表面吸附的动力学行为.今天，真正需要对固体表面上的化学反应机理的基本理解，因为先进的材料技术，如分子束外延，有机金属化学气相沉积和X射线/变化粒子光刻，基本上是基于表面化学过程。该新技术利用由撞击电子的电子激发引起的离子解吸。已知在电子激发时解吸的离子携带关于吸附在表面上的母体分子的吸附状态的丰富信息。解吸离子的详细分析将提供定量描述的势能面，无论是基态和激发态。我们还研究了一氧化碳与甲胺和乙炔的共吸附，Mo（112）的化学改性。

We have constructed a novel ion spectrometer, named time-of-flight Fourier-transform ion spectrometer (TOFFTIS), which has significantly high detection efficiency and high enegy resolution at very low energies. The TOFFTIS has been mounted on an ultrahigh-vacuum compatible two-axis rotation assembly and installed in an ultrahigh-vacuum chamber. As a prelimainary experiment, electron-stimulated desorption of O^+ and CO^+ has been successfully obtained, demonstrating that TOFFTIS has a performance as expected.By using TOFFTIS as a high-efficiency ion detector, we have developed a new experimental technique named angle-resolved electron-stimulated desorption spectroscopy (ARESDS) to investigate the dynamic behavior of excited species adsorbed on solid surfaces. Today, the basic understanding of the mechanism of chemical reactions on solid surfaces is truly demanded, since the advanced material technology, such as molecular-beam epitaxy, organometallic chemical vapor deposition, and X-ray/changed-particle lithogaphy, are based essentially on the surface chemical processes. The new technique utilizes the desorption of ions induced by electronic excitation by impinging electrons. The ions desorbed upon electronic excitations are known to carry rich information about the adsorption state of the parent molecules adsorbed on the surface. Detailed analysis of desorbed ions will provide quantitative description of the potential energy surface, both of ground and excited states. We have also studied on the coadsorption of carbon monoxide with methylamine and acetylene, the chemical modification of Mo(112) by chemisorbed oxygen atoms.