Autocorrelation function for the photodissociation of the v = 5 (black) and v = 15 (red) levels of the b 3Σ+ state towards higher excited 3Σ+ states
Figure 2. Autocorrelation function for the photodissociation of the v = 5 (black) and v = 15 (red) levels of the b 3Σ+ state towards higher excited 3Σ+ states. In the case of v = 5, two different timescales can clearly be observed (with the direct photodissociation contribution appearing before 2000 au of time), unlike in the case of v = 15.
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.