Ionic pathway studies in fragmentation of the core-excited (CH3)3SiBr molecule involving the Br(3d) and Si(2p) inner-shells in the range of 60 - 133 eV

Abstract

Dissociative multiple photoionization of bromotrimethylsilane [(CH3)3SiBr] has been probed in the valence, the Br(3d), and the Si(2p) core-level photoexcitation/photoionization regions by time-of-flight (TOF) mass spectrometry and photoion-photoion coincidence (PIPICO) method together with linearly polarized synchrotron radiation. The inner-shell photoionization spectra are dominated by a huge resonance attributed to the diffusion of the outgoing photoelectrons by the centrifugal barrier for the Br(3d9εf) outgoing channel. In addition to the giant resonance, discrete photoabsorption bands below the Br(3d5/2) and Si(2p3/2) thresholds have been observed in both the total photoion and PIPICO yield spectra. In the valence excitation/ionization region, single ionization leading to the formation of CnHpSiBr+(n=0-3), CnHpSi+(n=0-3), and CH3+ prevails. Above the Br(3d) threshold including the Si(2p) region, however, destruction of the three or more bonds could account for the dominant PIPICO channels leading to the formation of H+-CHp+(p=1-3) and CHn+-HpSi+(p=0,1) ion pairs. The exclusive formation of only the singly charged ions over the entire energy range indicates that charge redistribution is much faster than the bond cleavages. © 2002 Elsevier Science B.V. All rights reserved.