title: Photodissociation Electronic Spectra of Cold Protonated Quinoline and Isoquinoline in the Gas Phase.
abstract: Photofragmentation electronic spectra of isolated single-isomeric N-protonated quinoline (quinolinium) and isoquinoline (isoquinolinium) ions have been measured at a temperature of ∼40 K using a mass-selective, 10 cm-1spectral resolution, photodissociation spectrometer. Additionally, ab initio adiabatic transition energies calculated using the RI-ADC(2) method have been employed to assist in the assignment of the spectra. Three electronic transitions having ππ* character were clearly evidenced for both protonated ions within the UV and deep-UV spectral ranges. The corresponding spectra at room temperature were previously reported by Hansen et al., together with TD-DFT calculations and a careful analysis of the possible fragmentation mechanisms. This information will be complemented in the present study by appending better resolved spectra, characteristic of cold ions, in which well-defined vibrational progressions associated with the S1← S0and S3← S0transitions exhibit clear 0-0 bands at hν0-0= 27868 and 42230 cm-1, for protonated quinoline, and at hν0-0= 28043 and 41988 cm-1, for protonated isoquinoline. Active vibrations in the spectra were assigned with the help of calculated normal modes, looking very similar to those of the structurally related protonated naphthalene. Finally, we have observed that the bandwidths associated with the deep-UV S3← S0transition denote a lifetime for the S3excited state in the subpicosecond time scale, in contrast with that of S1.
authors.affiliation: CNRS, Aix-Marseille Université, PIIM UMR 7365 , Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Féraud
authors.affiliation: Facultad de Ciencias Exactas y Naturales, DQIAF, Universidad de Buenos Aires , Ciudad Universitaria, 1er piso, Pab. II, C1428EGA, Buenos Aires, Argentina.|Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-UBA , Ciudad Universitaria, 3er piso, Pab. II, C1428EGA, Buenos Aires, Argentina.
authors.forename: Luis
authors.initials: L
authors.lastname: Domenianni
authors.affiliation: Facultad de Ciencias Exactas y Naturales, DQIAF, Universidad de Buenos Aires , Ciudad Universitaria, 1er piso, Pab. II, C1428EGA, Buenos Aires, Argentina.|Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), CONICET-UBA , Ciudad Universitaria, 3er piso, Pab. II, C1428EGA, Buenos Aires, Argentina.
authors.forename: Ernesto
authors.identifier: http://orcid.org/0000-0002-7038-9950
authors.initials: E
authors.lastname: Marceca
authors.affiliation: CNRS, Aix-Marseille Université, PIIM UMR 7365 , Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Dedonder-Lardeux
authors.affiliation: CNRS, Aix-Marseille Université, PIIM UMR 7365 , Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jouvet