Development of New Analyzing Method of Excited States Using Combination of Soft X-Rays and Laser

为了发展新的激发态分析方法，我们在现有的高能角分辨光电子能谱仪和超快激光的基础上，构建了超快时间分辨光电子能谱系统。利用这一新系统，我们实现了对激光泵浦激发态光电子的测量。实验结果与激发态的计算结果进行了比较，表明了新的光谱方法的有效性。在Ag/Si表面上进行了能量和角度分辨光电子能谱研究。得到的能带能量色散曲线清楚地表明了新光谱的有效性。我们还安装了平面波荡器，以获得更高亮度的同步加速器光，并利用同步加速器光和激光在高重复频率方面的优势，对单色仪系统进行了调谐，用于联合实验。我们已经构建了新的双光子光电子能谱系统。利用该系统，我们成功地测量了n型和p型GaAs的超快时间分辨光电子能谱。这一结果对于研究表面光伏效应的动力学特性具有重要的意义。本项目取得的部分成果已在国际会议和期刊上作了报告。

In order to develop the new analyzing method for excited states, we have constructed the ultra-fast time-resolved photoelectron spectroscopy system based on the existing high energy and angle-resolved photoelectron spectrometer and the ultra-fast laser. Using this new system, we have carried out the measurement of the photoelectrons from the excited-states pumped by laser-light. The experimental results were compared with the calculation of the excited states, indicating the performance of the present new spectroscopy. The energy and angle-resolved photoelectron spectroscopy has been conducted on Ag/Si surfaces. The obtained energy dispersion curves of the bands indicate clearly the validity of the present new spectroscopy. We have also installed the planar undulator to obtain the higher brilliant synchrotron light and tuned up the monochromator system for combination experiments using synchrotron light and laser that have advantage in the high repetition frequency. We have constructed the new two-photon photoelectron spectroscopy system. Using this system we have successfully measured the ultra-fast time-resolved photoelectron spectra on n-and p-type GaAs. The result is very interesting and attractive to investigate the dynamics of the surface photo-voltage effect. A part of the results obtained in the present project has been reported in the international conference and Journals.