12350-21-9Relevant academic research and scientific papers
Photoionisation Mass-spectrometric Study of Fragmentation of SiBr4 and GeBr4 in the Range 400-1220 Angstroem
Creasey, Jeremy C.,Lambert, Ian R.,Tuckett, Richard P.,Codling, Keith,Frasinski, Leszek J.,et al.
, p. 3717 - 3724 (1991)
The non-radiative decay channels of the valence electronic states of SiBr4+ and GeBr4+ have been studied in the range 1220-400 Angstroem (10-31 eV) by photoionisation mass spectrometry.Ion-yield curves for the parent ions and for MBr3+, MBr2+, MBr+, M+ and Br+ (M = Si, Ge) have been obtained, as well as the relative photoionisation branching rations.The appearance thresholds for SiBr3+ and GeBr3+ occur at 11.31 and 10.97 eV, respectively.They lie within the Franck-Condon region of the ground state of SiBr4+ and GeBr4+, and are at the thermodynamic thresholds for SiBr3+ + Br and GeBr3+ + Br.The smaller fragment ions have appearance thresholds which relate to energies for excited electronic states of SiBr4+ and GeBr4+, and not to the lower-lying thermodynamic energy of the fragment ion.The results are discussed with reference to our earlier work on radiative decay from excited states of SiBr4+ and GeBr4+ (J.Chem.Soc.Faraday Trans., 1990, 86, 2021).We have obtained a new value for the ionisation potential of SiBr3 of 7.6 +/- 0.4 eV, and we suggest that the previously accepted value for SiBr2 (12 +/- 1 eV) is ca. 3.5 eV too high.
