Electronic spectroscopy of carbon chains (C2n+1, n=7-10) of astrophysical importance. II. Quantum dynamics

摘要

In continuation with Paper I [S. R. Reddy et al., J. Chem. Phys. 151, 054303 (2019)], the vibronic structure and dynamics of the (1)Sigma(+)(u) electronic state of C-15, C-17, C-19, and C-21 chains in the coupled manifold of (1)Sigma(+)(u)-(1)Pi(g)-(1)Pi(u)-(1)Sigma(+)(g) electronic states have been investigated in this paper. The model vibronic Hamiltonian developed through extensive ab initio quantum chemistry calculations in Paper I is employed, and first principles nuclear dynamics calculations are carried out to obtain the photoabsorption band of the (1)Sigma(+)(u) electronic state. Both time-independent and time-dependent quantum mechanical calculations are carried out to precisely locate the vibrational levels, assign them with the progression of vibrational modes, and elucidate the impact of both Renner-Teller and pseudo-Renner-Teller couplings on them. The nonradiative decay of the (1)Sigma(+)(u) electronic state is studied, and it is found that the decay rate is comparable with the prediction made for them to be qualified as a carrier of diffuse interstellar bands in the literature. The theoretical results are found to be in good accord with the available experimental results. Published under license by AIP Publishing.