[en] nonadiabatic coupling ; electronic states interacting with a continuum ; correlation function
[fr] resonance states ; predissociation ; HBr cation
[en] The Fourier transform of an electronic spectrum leads to an autocorrelation function which provides information on the propagation of the wave packet on the potential energy surface of the electronic state reached in the transition. The formula is valid even when nonadiabatic interaction is present, i.e., when the wave packet splits at a particular surface crossing with one part branching off to another potential energy surface. An explicit expression of the correlation function is given for a model of several discrete states interacting with a continuum. Closed-form solutions are given in the case of one and two resonances. A very simple formula valid in the strong coupling limit is also derived. The method is applied to the photoelectron spectrum of state A 2Sigma+ of HBr+, which is shown to correspond to the strong couplig case.
Fonds de la Recherche Fondamentale Collective d’Initiative des Chercheurs - FRFC ; Fonds pour la formation à la Recherche dans l'Industrie et dans l'Agriculture (Communauté française de Belgique) - FRIA ; Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy