Site-specific dissociation of (CH 3) 3SiI involving I(4d), Si(2p), C(1s) and I(3d) inner-shell excitations in the range of 88–1000 eV

Abstract

Dissociative multiple photoionization of iodotrimethylsilane [(CH 3) 3SiI] has been investigated in the I(4d), Si(2p), I(4p), I(4s), C(1s), I(3p), and I(3d) core level excitation/ionization regions in the range from 88 to 1000 eV by time-of-flight (TOF) mass spectrometry and the photoion–photoion coincidence (PIPICO) method coupled to synchrotron radiation. The inner-shell spectra below 160 eV are dominated by a powerful giant resonance which has been identified as a resonance owing to the diffusion of the outgoing photoelectrons by the centrifugal barrier in the I(4d 9ϵf) outgoing channel. In addition to the huge resonance, discrete photoabsorption bands around the Si(2p) (106.77 eV) and the C(1s) (289.95 eV) edges are observed in both the total photoion and PIPICO yield spectra. Site-selective dissociation patterns were elucidated by the coincident measurements of the fragment ions formed via a single photon absorption. At low energies below the Si(2p) threshold region (88–107 eV), dissociation pathways leading to the formation of H +–I 2+ and H +–I + are dominant. Above the energy, however, near total destruction giving rise to CH 3 +–SiH +, H +–CH p + ( p=0–3), H +–SiH p + ( p=0–3), SiCH n +–I +, and H +–SiCH p + ( p=0–5) are dominant.