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A&A 421, 381-386 (2004)
DOI: 10.1051/0004-6361:20035871
Effect of non-adiabatic coupling on the isotopic dependence of the photodissociation cross section of CO
L. Andric1, F. Bouakline1, T. P. Grozdanov2 and R. McCarroll11 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
(Received 16 December 2003 / Accepted 15 March 2004)
Abstract
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
Offprint request: R. McCarroll, mccarrol@ccr.jussieu.fr
© ESO 2004