title: Photon induced isomerization in the first excited state of the 7-azaindole-(H2O)3 cluster.
abstract: A picosecond pump and probe experiment has been applied to study the excited state dynamics of 7-azaindole-water 1 ∶ 2 and 1 ∶ 3 clusters [7AI(H(2)O)(2,3)] in the gas phase. The vibrational-mode selective Excited-State-Triple-Proton Transfer (ESTPT) in 7AI(H(2)O)(2) proposed from the frequency-resolved study has been confirmed by picosecond decays. The decay times for the vibronic states involving the ESTPT promoting mode σ(1) (850-1000 ps) are much shorter than those for the other vibronic states (2100-4600 ps). In the (1 + 1) REMPI spectrum of 7AI(H(2)O)(3) measured by nanosecond laser pulses, the vibronic bands with an energy higher than 200 cm(-1) above the origin of the S(1) state become very weak. In contrast, the vibronic bands in the same region emerge in the (1 + 1') REMPI spectrum of 7AI(H(2)O)(3) with picosecond pulses. The decay times drastically decrease when increasing the vibrational energy above 200 cm(-1). Ab initio calculations show that a second stable "cyclic-nonplanar isomer" exists in addition to a "bridged-planar isomer", and that an isomerization from a bridged-planar isomer to a cyclic-nonplanar isomer is most probably responsible for the short lifetimes of the vibronic states of 7AI(H(2)O)(3).
authors.affiliation: INFIQC, Centro Láser de Ciencias Moleculares, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina. gpino@fcq.unc.edu.ar
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Pino
authors.forename: Ivan
authors.initials: I
authors.lastname: Alata
authors.forename: Claude
authors.initials: C
authors.lastname: Dedonder
authors.forename: Christophe
authors.initials: C
authors.lastname: Jouvet
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakota
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekiya
mesh_terms: D007211:Indoles / Q000737:chemistry*; D007536:Isomerism; D015394:Molecular Structure; D017785:Photons; D011789:Quantum Theory; D014867:Water / Q000737:chemistry*
chemical_list: C023422:7-azaindole dimer; D007211:Indoles; D014867:Water