title: Photofragmentation mechanisms in protonated chiral cinchona alkaloids.
abstract: The photo-stability of protonated cinchona alkaloids is studied in the gas phase by a multi-technique approach. A multi-coincidence technique is used to demonstrate that the dissociation is a direct process. Two dissociation channels are observed. They result from the C8-C9 cleavage, accompanied or not by hydrogen migration. The branching ratio between the two photo-fragments is different for the two pseudo-enantiomers quinine and quinidine. Mass spectrometry experiments coupling UV photo-dissociation of the reactants and structural characterization of the ionic photo-products by Infra-Red Multiple Photo-Dissociation (IRMPD) spectroscopy provide unambiguous information on their structure. In addition, quantum chemical calculations allow proposing a reactive scheme and discussing it in terms of the ground-state geometry of the reactant.
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Sunil
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Bruno
authors.initials: B
authors.lastname: Lucas
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Fayeton
authors.affiliation: Univ. Paris-Sud, Laboratoire de Chimie Physique, UMR8000, and CNRS, Orsay, F-91405, France.
authors.forename: Debora
authors.initials: D
authors.lastname: Scuderi
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Ivan
authors.initials: I
authors.lastname: Alata
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Michel
authors.initials: M
authors.lastname: Broquier
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Katia Le
authors.initials: KL
authors.lastname: Barbu-Debus
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Valeria
authors.initials: V
authors.lastname: Lepère
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France. anne.zehnacker-rentien@u-psud.fr.
authors.forename: Anne
authors.initials: A
authors.lastname: Zehnacker