Effect of non-adiabatic coupling on the isotopic dependence of the photodissociation cross section of CO
Laboratoire de Chimie Physique-Matière et Rayonnement (UMR 7614 du CNRS), Université Pierre et Marie Curie, 75231 Paris Cedex 05, France
2 Institute of Physics, PO Box 57, 11001-Belgrade, Serbia and Montenegro
Corresponding author: R. McCarroll, email@example.com
Accepted: 15 March 2004
Calculations of the photodissociation cross sections of CO from the ground X state into the coupled Rydberg B state and the valence dissociative D state have been carried out using the smooth exterior complex scaling (SECS) method. Results are presented for all of the 6 isotopomers involving the 12C, 13C, 16O, 17O and 18O isotopes. The absorption profiles of the predissociating resonances induced by non-adiabatic coupling vary considerably from one isotopomer to another. It is confirmed that resonance widths obtained simply from a diagonalization of the complex Hamiltonian do not give a true indication of the absorption profile. A correct profile is only obtained when the sum over all resonant and non-resonant continuum states is performed. A brief discussion is given of the implications for isotopic fractionation in interstellar CO.
Key words: astrochemistry / ISM: molecules / molecular processes / ultraviolet: ISM
© ESO, 2004