Direct Observation of Internal Rotational Motion of Molecules Absorbed on a Surfaces

在这个研究项目上，我们改进了我们的实验仪器。该装置已经能够进行激光诱导荧光实验，经过目前的改进，也可以在该装置上进行激光电离实验。利用改进后的装置，我们尝试观察了CO、CN等轻金属表面的吸附分子，并成功地测量了一些新的分子吸附体系的新光谱。通过对观察到的光谱的分析，我们得到了一些关于吸附物种内旋转运动的新信息。本项目的研究结果将为吸附表面吸附分子的控制提供有用的指导。实验装置经过本研究经费的改进后，可以进行激光电离实验，其灵敏度高于现有的激光诱导荧光法，并利用这一新技术成功地观察到了新的分子吸附体系，因为它具有更高的灵敏度。研究发现，在SiCN/SiC体系中，CN物种的内旋转运动具有相当复杂的机制。对于Al和Ng体系，我们分析了一些内旋转运动势，清楚地表明内旋转运动势与分子吸附体系有很强的依赖关系。结果表明，四次非谐项在体系的势能中占主导地位，而对于MgNC/MgCN体系，势能可以用三角函数来描述。

On this research project, we have improved our experimental apparatus. The apparatus had been already enable to carried out the laser induced fluorescence experiments, and, after the present improvements, the laser ionization experiments could also be performed on this apparatus. Using this improved apparatus, we tried to observe adsorbed molecules, such as CO,CN, etc., on light metal surfaces, such as, Mg, Al, and Si, and we have succeeded to measure new spectra of some new molecular adsorbed systems. From the analysis of the observed spectra, we have obtained some new information on the internal rotational motion of the adsorbed species. The results of this project would provide useful guide to control of adsorbed molecules on the adsorbed surfaces.ApparatusAfter the improvements on our experimental apparatus executed by this research budget, it could perform the laser ionization experiments, which is higher sensitivity than the laser induced fluorescence method that we had, and using this new technique, we succeeded to observe new molecular adsorbed systems, because of the higher sensitivity.Experimental resultsWe succeeded to observe Si cluster systems, such as SiCCH, SiCN, and SiNC. It is found for the SiCN/SiNC system that the internal rotation motion of the CN species has quite complicated mechanism. For the Al and Ng systems, we analyzed some internal rotation motion potentials, and clearly showed that the potential has quite strong dependence upon the molecular adsorbed system. It was found that the 4th order anharmonic term is predominant for the potential of the MgOH system, and that the potential can be well described by the trigonometrical function for the MgNC/MgCN system.