title: Direct observation of spin-forbidden transitions through the use of suitably polarized light.
abstract: The study of excited triplet states of a molecular system is a difficult task because accessing them involves forbidden transitions from the singlet ground state. Nevertheless, absorption spectra of many molecules present, at low energies, the weak fingerprint of these triplet states. At higher energies this information is usually masked by the intense signal of the singlet states. Here we show, for the specific case of the sulphur dioxide molecule, that the combined use of polarized light and molecular alignment can enhance the triplet part of the spectrum, even making it the only absorption process.
authors.affiliation: 1] Sorbonne Universités, Laboratoire de Chimie Physique-Matière et Rayonnement, UPMC Univ. Paris 06, UMR 7614, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France [2] CNRS, LCPMR, UMR 7614, Paris Cedex 05 France [3] Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, Heidelberg D-69120, Germany.
authors.forename: Camille
authors.initials: C
authors.lastname: Lévêque
authors.affiliation: Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, Heidelberg D-69120, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Peláez
authors.affiliation: Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, Heidelberg D-69120, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Köppel
authors.affiliation: 1] Sorbonne Universités, Laboratoire de Chimie Physique-Matière et Rayonnement, UPMC Univ. Paris 06, UMR 7614, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05, France [2] CNRS, LCPMR, UMR 7614, Paris Cedex 05 France.
authors.forename: Richard
authors.initials: R
authors.lastname: Taïeb