title: IR spectroscopy of the 4-aminobenzonitrile-Ar cluster in the S0, S1 neutral and D0 cationic states.
abstract: The S1-S0 resonant enhanced multiphoton ionization (REMPI) spectrum as well as the infrared (IR) spectra in the S0 and S1 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 S0 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 S1, 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.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Ishiuchi
authors.forename: Martin
authors.initials: M
authors.lastname: Weiler
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmies
authors.forename: Otto
authors.initials: O
authors.lastname: Dopfer
authors.forename: Masaaki
authors.initials: M
authors.lastname: Fujii
mesh_terms: D001128:Argon / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D009570:Nitriles / Q000737:chemistry*; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: D002412:Cations; D009570:Nitriles; D001128:Argon; C045271:4-aminobenzonitrile