Pathway studies in Si(2p) inner-shell processes of H2Si(CH3)2 by mass spectrometry and the photoion -: Photoion coincidence method in the range 24-133 eV

Dissociative multiple photoionization processes of dimethylsilane (H2Si(CH3)(2)) have been investigated in the valence and Si(2p) core level photoexcitation/photoionization regions by time-of-flight (TOF) mass spectrometry coupled to synchrotron radiation, operated in both the photoelectron-photoion coincidence (PEPICO) and photoion-photoion coincidence (PIPICO) modes. Two group absorption bands below and above the Si(2p(3/2)) threshold 106.51 eV are observed in both total photoion and PIPICO yield waves. Various monocations of H-n(+)(n = 1-3), CHn+(n = 0-4), C2Hn+(n = 1-3), SiC2Hn+(n = 0-3), SiCHn+(n = 0-5), SICHn+(n = 0-7) are observed. the yields depending on the excitation energy. In the valence ionization region, especially E < 30 eV, extrusions of H, H-2, CH3, and of CH4 (or H + CH3) and CH3 + H-2 (or H + CH4), are predominantly observed leading to the formation of SiC2Hn+ (n = 6, 7) and SiCHn+(n = 3-5), respectively, whereas in the Si(2p) excitation and ionization regions, ionic fragments of smaller masses such as H+, CH3+, Si+, and SICH3+ are relatively abundant in the PEPICO spectra. Bond-selective fragmentation processes occur in the two absorption regions. An ab initio calculation was also carried out to predict discrete excitation energies and their modes corresponding to the transitions from the core to valence and Rydberg orbitals.