The vibrational structure of the oxygen K-shell spectra in acenaphthenequinones: an ab initio study.
The vibrational structure of the K-shell O1s → π∗ of acenaphthenequinone C(12)H(6)O(2) and its halogenated compound C(12)H(2)Br(2)Cl(2)O(2) has been simulated using an entirely ab initio approach. For both molecules, analysis of the calculated Franck-Condon factors confirm without ambiguity that, contrary to initial claims, the C-H stretching modes are not modified in the core states and are not excited. For C(12)H(6)O(2), the vibrational fine structure appears to be mainly due to three modes, involving C=O∗ asymmetric stretch and in-plane ring deformation modes, due to the symmetry breaking of the core state. For C(12)H(2)Br(2)Cl(2)O(2), the vibrational excitation arises essentially from the C=O∗ asymmetric stretch, with numerous secondary peaks arising from hot and combination bands. For both molecules, these bands are probably responsible for the asymmetry deduced in the experimental fits using a unique Morse potential and initially assigned to anharmonic effects.
Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Université Lille1 Sciences et Technologies, F-59655 Villeneuve d'Ascq Cedex, France. Denis.Duflot@univ-lille1.fr
Denis
D
Duflot
Jean-Pierre
JP
Flament