title: Infrared Photodissociation Spectroscopy of C4N-, C6N-and C8N.
abstract: The gas-phase vibrational spectroscopy of cold C2nN-(n=2-4) anions is investigated in the CC and CN multiple bond stretching region (1700-2250 cm-1) by means of infrared photodissociation (IRPD) spectroscopy in a cryogenically cooled ion trap of the corresponding messenger-tagged complexes. The IRPD spectra are assigned to N-terminated linear structures with triplet ground states (3Σ-) based on a comparison with harmonic vibrational frequencies and intensities from density functional theory computations. In contrast to the polyacetylenic C2n+1N-anions, the linear C-C chains investigated here exhibit cumulenic character, which is most pronounced in C4N-and decreases with chain length. Additional intense transitions are observed for C6N-above 3000 cm-1and are attributed to overtone and combination bands involving the CC stretching modes, based on anharmonic computations. The influence of a D2tag on the vibrational features of C2nN-anions is shown to be small.
authors.affiliation: Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: E Cristina
authors.initials: EC
authors.lastname: Stanca-Kaposta
authors.affiliation: Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: Falko
authors.initials: F
authors.lastname: Schwaneberg
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195, Berlin, Germany.|Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103, Leipzig, Germany.
authors.forename: Matias R
authors.identifier: http://orcid.org/0000-0003-4759-8110
authors.initials: MR
authors.lastname: Fagiani
authors.affiliation: Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lalanne
authors.affiliation: Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
authors.forename: Ludger
authors.initials: L
authors.lastname: Wöste
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195, Berlin, Germany.|Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103, Leipzig, Germany.
authors.forename: Knut R
authors.identifier: http://orcid.org/0000-0001-6297-5856
authors.initials: KR
authors.lastname: Asmis
keywords: anharmonicity; cryogenic ion trap; density functional theory; infrared photodissociation; interstellar anions