title: Electronic Spectroscopy of Protonated 1-Aminopyrene in a Cold Ion Trap.
abstract: In aromatic systems that contain an amino group, there is competition between protonation on a carbon atom of the skeleton and protonation on the amino group. Herein, we studied the photofragmentation of protonated 1-aminopyrene in a cold ion trap and mainly observed the protonated amino tautomer, which led to fragmentation pathways through the loss of H or NH3groups. Several excited states were assigned, among which the fourth excited state showed broadened bands, thus indicating a fast decay that was attributed to the presence of a πσ* charge-transfer state by comparison of the experimental results with ab initio calculations. We deduced the πσ* transition energies in protonated aromatic amino compounds of increasing size directly from the ionization potentials of the neutral aromatic unsubstituted molecules. Tautomers that were protonated on a carbon atom of the pyrene skeleton were also weakly observed, and we showed that two tautomers that were protonated on a carbon atom of the aromatic ring could be distinguished by using electronic spectroscopy.
authors.affiliation: Institut des Sciences Moléculaires (ISM, UMR 5255), Université de Bordeaux and CNRS, 351 Cours de la Libération, F-33405, Talence, France.
authors.forename: Jennifer Anna
authors.initials: JA
authors.lastname: Noble
authors.affiliation: CNRS, Aix-Marseille Université, PIIM UMR 7345, Avenue Escadrille Normandie-Niémen, 13397, Marseille Cedex 20, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Dedonder-Lardeux
authors.affiliation: Institut des Sciences Moléculaires (ISM, UMR 5255), Université de Bordeaux and CNRS, 351 Cours de la Libération, F-33405, Talence, France.
authors.forename: Joëlle
authors.initials: J
authors.lastname: Mascetti
authors.affiliation: CNRS, Aix-Marseille Université, PIIM UMR 7345, Avenue Escadrille Normandie-Niémen, 13397, Marseille Cedex 20, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jouvet
keywords: ab initio calculations; electronic spectroscopy; ion trap; nitrogen heterocycles; protonation