Rate constants for the photodissociation of the b ³Σ⁺ state as a function of the temperature T_* of the blackbody, for different Maxwell–Boltzmann distribution temperatures T_{M − B}

Figure 8. Rate constants for the photodissociation of the b ³Σ⁺ state as a function of the temperature T_* of the blackbody, for different Maxwell–Boltzmann distribution temperatures T_{M − B}. The T_MB = 2 result, for which only the v'' = 0, J'' = 0 level is populated, is obtained for all Maxwell–Boltzmann distribution temperatures if the vibrational dependence of the cross section is neglected, as the photodissociation cross sections for all v'', J'' levels are then assumed to be equal to the cross section for the v'' = 0, J'' = 0'' level.

Abstract

We illustrate some of the difficulties that may be encountered when computing photodissociation and radiative association cross sections from the same time-dependent approach based on wavepacket propagation. The total and partial photodissociation cross sections from the 33 vibrational levels of the b ³Σ⁺ state of HeH⁺ towards the nine other ³Σ⁺ and 6 ³Π n = 2, 3 higher lying electronic states are calculated, using the autocorrelation method introduced by Heller (1978 J. Chem. Phys. 68 3891) and the method based on the asymptotic behaviour of wavepackets introduced by Balint-Kurti et al (1990 J. Chem. Soc. Faraday Trans. 86 1741). The corresponding radiative association cross sections are extracted from the same calculations, and the photodissociation and radiative association rate constants are determined.