He^{*}(2 ^{3}S) Penning ionization of H_{2}S. I. Theoretical FranckCondon factors for the H_{2}S(X∼ ^{1}A_{1},v^{'}=0)→H_{2}^{S+}(X∼ ^{2}B_{1},Ã ^{2}A_{1}) ionization and H_{2}S^{+}(ÖX∼) transition
Abstract
In order to elucidate the ionization dynamics, in particular the vibrational distribution, of H_{2}S^{+}(Ã) produced by the Penning ionization of H_{2}S with He^{*}(2 ^{3}S) atoms, the FranckCondon factors (FCFs) were presented for the H_{2}S(X∼)→H_{2}S^{+}(X∼,Ã) ionization and the H_{2}S^{+}(ÖX∼) transition, and Einstein's A coefficients were presented for the latter transition. The FCFs were obtained by quantum vibrational calculations using the global potential energy surfaces (PESs) of H_{2}S(X∼ ^{1}A_{1}) and H_{2}S^{+}(X∼ ^{2}B_{1},Ã ^{2}A_{1},B∼ ^{2}B_{2}) electronic states. The global PESs were determined by the multireference configuration interaction calculations with the Davidson correction and the interpolant moving least squares method combined with the Shepard interpolation. The obtained FCFs exhibit that the H_{2}S^{+}(X∼) state primarily populates the vibrational ground state since its equilibrium geometry is almost equal to that of H_{2}S(X∼), while the bending mode (ν_{2}) is strongly enhanced for the H_{2}S^{+}(Ã) state; the maximum in the population is around ν_{2}=67. In the same manner, the bending progressions are expected to consist of the great part of the H_{2}S^{+}(ÖX∼) emission. A detailed comparison with the experimental study for this system is reported in the accompanying paper, Paper II.
 Publication:

Journal of Chemical Physics
 Pub Date:
 September 2003
 DOI:
 10.1063/1.1602063
 Bibcode:
 2003JChPh.119.5874T
 Keywords:

 33.70.Ca;
 Oscillator and band strengths lifetimes transition moments and FranckCondon factors