Site-Specific Electron-Relaxation Caused by Si:2p Core-Level Photoionization: Comparison between F3SiCH2CH2Si(CH3)3 and Cl3SiCH2CH2Si(CH3)3 Vapors by Means of Photoelectron Auger Electron Coincidence Spectroscopy

Site-specific electron relaxations caused by Si:2p core-level photoionizations in F3SiCH2CH2Si(CH3)3 and Cl3SiCH2CH2Si(CH3)3 vapors have been studied by means of the photoelectron Auger electron coincidence spectroscopy. F3SiCH2CH2Si(CH3)3 shows almost 100% site-specificity in fragmentation caused by the Si:2p ionization. However, substitution of Cl for F of F3SiCH2CH2Si(CH3)3 considerably reduces the site-specificity at the Si atom bonded to three halogen atoms, with the site-specificity at the Si site bonded to three methyl groups remaining largely unchanged. The site-specificity reduction in Cl3SiCH2CH2Si(CH3)3 is considered to take place during the transient period between Si:L23VV Auger electron emission and the subsequent fragmentation. The reason for the reduction can be explained in terms of some differences between these two molecules in the L23VV Auger decay at the Si site bonded to the three halogen atoms.