| Research Abstract |
As an in-situ observation technique of synchrotron radiation stimulated processes, infrared reflection absorption spectroscopy using buried metal layer substrate ( BML-IRRAS ), and scanning tunneling electron microscopy ( STM ) techniques were developed, and applied to the atom and molecular level characterization of the surface reaction was investigated. Furthermore, as an supporting experimental apparatus to investigate the excitation energy dependence of the synchrotron radiation stimulated process, high flux monochromator-multilayered mirror monochromator- and electron ion coincidence technique were developed.
1. BML-IRRAS has characteristics of high sensitivity and covering wide frequency range including finger print regions. The surface vibrations of hydrogen chemisorbed Si ( 100 ) surface with 3 x 1 and 1 x 1 structures are investigated by BML-IRRAS. It is clearly observed for the first time that SiHィイD22ィエD2 bend scissors mode splits to two distinct peaks locating at 902 and 913
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cmィイD1-1ィエD1, which are assigned to isolated dihydride ( ID ) and adjacent dihydride (AD ) species, respectively. From the annealing temperature dependence of the spectra, it is also found that two symmetric stretching peaks of 2107 and 2091 cmィイD1-1ィエD1 reported previously are assigned to the vibrational modes of AD and ID, respectively.
2. The surface morphology of Si ( 111 ) was investigated using scanning tunneling microscopy after desorption of surface SiOィイD22ィエD2, by synchrotron radiation illumination. The surface shows large regions of atomically flat Si ( 111 )-7x7 structure, and is characterized by the formation of single bilayer steps nicely registered to the underlying crystal structure. This is in sharp contrast to Si ( 111 ) surfaces after thermal desorption of SiOィイD22ィエD2 at temperatures 880℃ and above, where the surface steps are much more irregular. The registration of the surface steps to the underlying crystal structure indicates that the Si (111 ) surface reaches thermodynamic equilibrium under synchrotron radiation irradiation at temperatures much lower than that necessary for thermal desorption. Less
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