PHOTOELECTRON-SPECTRA OF ORGANOMETALLIC COMPOUNDS CONTAINING SILICON-SILICON AND SILICON-GERMANIUM BONDS - VALENCE-BAND STUDIES

Valence band photoelectron spectra have been recorded at 21.2-, 100-, 120-, and 135-eV photon energies for the following five compounds: Si( CH3)(4), Si-2(CH3)(6), Si[Si(CH3)(3)](4), Ge[Si-(CH3)(3)](4), and [Si( CH3)(2)](6). The ground-state energies from the MS-X alpha method are used to assign the photoelectron spectra. The photon energy dependence of the intensities, combined with Gelius model intensity predictions from the MS-X alpha molecular orbital compositions, confirms the molec ular orbital ordering. The peak at lowest binding energy at similar to 8 eV (not present in Si(CH3)(4)) results from the Si-Si or Si-Ge bond ing orbitals. The second peak at similar to 10 eV results from orbital s associated primarily with Si-C bonds, while the next overlapping thr ee peaks mainly result from C-H bonding orbitals. In [Si(CH3)(2)](6), the second Si-C peak splits into two because of the two axial and equa torial positions of the methyl groups in the six-membered silicon ring .