NDLI: Photodissociation UV-Vis Spectra of Cold Protonated Azobenzene and 4-(Dimethylamino)azobenzene and Their Benzenediazonium Cation Fragment.

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Jouvet, Christophe Marceca, Ernesto Féraud, Géraldine Dedonder-lardeux, Claude
Description	Author Affiliation: Féraud G ( CNRS, Aix-Marseille Universite Ì , PIIM UMR 7365, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.); Dedonder-Lardeux C ( CNRS, Aix-Marseille Universite Ì , PIIM UMR 7365, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.); Jouvet C ( CNRS, Aix-Marseille Universite Ì , PIIM UMR 7365, Avenue Escadrille Normandie-Niémen, 13397 Marseille Cedex 20, France.); Marceca E ( INQUIMAE, FCEN-UBA, Ciudad Universitaria , 3er piso, Pabellón II, C1428EGA Buenos Aires, Argentina.)
Abstract	Gas phase photodissociation electronic spectra of protonated azobenzene (ABH(+)) and 4-(dimethylamino)azobenzene (dmaABH(+)) were measured in a cryogenically cooled ion trap at temperatures of a few tens of Kelvin. Experimental results were complemented with electronic structure calculations in the ground state at the MP2/cc-pVDZ level of theory, and in the low lying excited states using the RI-CC2 method. Calculated energies revealed that only the trans isomers of the azonium molecular ions (protonation site on the azo group) will likely exist in the trap at the temperatures achieved in the experiment. The first transition of trans-ABH(+) is π* â π, and the absorption band in the spectrum appears strongly red-shifted from that of the neutral molecule. The calculations showed that upon excitation the quasi-planar ground state (S0) transforms into a chairlike excited state (S1) by twisting the CNNC dihedral angle about 96°. A 41 cm(-1) active vibrational progression found in the ABH(+) spectrum may be associated with the twisting of the azo bond. Conversely, the electronic spectrum of dmaABH(+) exhibits a steep and unstructured S1 â S0 absorption corresponding to a less distorted S1 state. The next two quasi-degenerate bands in the ABH(+) spectrum evidence sharper onsets and a charge transfer character. Using a second fragmentation laser and an additional He cooling pulse in the trap, it was possible to measure the UV spectrum of cold benzenediazonium fragments.
ISSN	10895639
Issue Number	22
Journal	The Journal of Physical Chemistry A
Volume Number	120
e-ISSN	15205215
Language	English
Publisher	American Chemical Society (United States)
Publisher Date	2016-06-09
Publisher Place	United States
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Physical chemistry
Content Type	Text
Resource Type	Article
Subject	Medicine Physical and Theoretical Chemistry

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