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IR Spectroscopy of the 4‐Aminobenzonitrile–Ar Cluster in the S 0 , S 1 Neutral and D 0 Cationic States
Author(s) -
Nakamura Takashi,
Miyazaki Mitsuhiko,
Ishiuchi Shunichi,
Weiler Martin,
Schmies Matthias,
Dopfer Otto,
Fujii Masaaki
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201200821
Subject(s) - van der waals force , chemistry , photoionization , overtone , infrared spectroscopy , spectroscopy , infrared , dissociation (chemistry) , ionization , photodissociation , van der waals molecule , atomic physics , spectral line , ion , photochemistry , molecule , physics , organic chemistry , quantum mechanics , astronomy , optics
The S 1 –S 0 resonant enhanced multiphoton ionization (REMPI) spectrum as well as the infrared (IR) spectra in the S 0 and S 1 states of 4‐aminobenzonitrile (4ABN) and its van der Waals complex with Ar (4ABN–Ar) were measured by means of IR depletion spectroscopy (REMPI–IR). The IR spectrum of 4ABN–Ar in S 0 shows symmetric and antisymmetric NH stretching vibrations ( ν s and ν a ) of the amino group at the same positions as those in the 4ABN monomer. This suggests that the Ar ligand locates above the benzene ring by van der Waals interactions (π‐bound). The same coincidence of vibrational frequencies was found in S 1 , and the π‐bound geometry was kept by the electronic excitation. The REMPI–IR spectrum of 4ABN + –Ar was also measured, and three major vibrational transitions were found. From the comparison to the IR dissociation spectrum with an electron impact source (EI–IR), they were assigned to ν s , ν a and an NH‐bending overtone of the π‐bound structure. It is concluded that photoionization of 4ABN + –Ar does not promote site‐switching of Ar from the π‐site to the H‐site.