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Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Infrared Photodissociation Spectroscopy of C4 N- , C6 N- and C8 N
E Cristina Stanca-Kaposta1, Falko Schwaneberg1, Matias R Fagiani2,3
1Fachbereich Physik, Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
Abstract:
The gas-phase vibrational spectroscopy of cold C2n N- (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 (3 Σ- ) based on a comparison with harmonic vibrational frequencies and intensities from density functional theory computations. In contrast to the polyacetylenic C2n+1 N- anions, the linear C-C chains investigated here exhibit cumulenic character, which is most pronounced in C4 N- and decreases with chain length. Additional intense transitions are observed for C6 N- above 3000 cm-1 and are attributed to overtone and combination bands involving the CC stretching modes, based on anharmonic computations. The influence of a D2 tag on the vibrational features of C2n N- anions is shown to be small.
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