Photolysis Studies of CF3Br Adsorbed on Si(111)-7×7 Near Si(2p) Edge

• Main Authors: Tzu-Ming Ho, 何子鳴
• Other Authors: Ching-Rong Wen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/06643788033602885268

碩士 === 國立成功大學 === 物理學系碩博士班 === 96 === The continuous-time photoelectron spectroscopy (PES) was employed to study the photolysis of CF3Br molecules adsorbed on Si(111)-7×7. Evolution of adsorbed CF3Br was monitored at two photon energies of 98 eV and 120 eV. By the first PES spectrum, we know that CF3Br molecules physisorb on Si surface molecularly. The sequential PES spectra show the variation of their shapes with photon exposure. This change indicates that the adsorbed CF3Br molecule has high photolysis cross section. The dissociation of CF3Br is mainly due to dissociative electron attachment and dipolar dissociation induced by photoelectrons. The photoelectrons emitting from the silicon surface are produced by the incident photons. From the variation of the 3a1 obital of CF3Br with photon exposure, we can obtain the photolysis cross section at different photon energies. The photolysis cross sections that we obtained were 3.6×10-18 cm2 at 98 eV photons and 6.2×10-18 cm2 at 120 eV photons, respectively. The difference of these two photolysis cross sections is due to the fact that the 120 eV photons can ionize the Si(2p) core-level of silicon substrate, and the following Auger process will produce Auger electrons resulting in the higher emission of low-energy electrons.