title: Photoionization-induced water migration in the amide group of trans-acetanilide-(H2O)1 in the gas phase.
abstract: IR-dip spectra of trans-acetanilide-water 1:1 cluster, AA-(H(2)O)(1), have been measured for the S(0) and D(0) state in the gas phase. Two structural isomers, where a water molecule binds to the NH group or the CO group of AA, AA(NH)-(H(2)O)(1) and AA(CO)-(H(2)O)(1), are identified in the S(0) state. One-color resonance-enhanced two-photon ionization, (1 + 1) RE2PI, of AA(NH)-(H(2)O)(1) via the S(1)-S(0) origin generates [AA(NH)-(H(2)O)(1)](+) in the D(0) state, however, photoionization of [AA(CO)-(H(2)O)(1)] does not produce [AA(CO)-(H(2)O)(1)](+), leading to [AA(NH)-(H(2)O)(1)](+). This observation explicitly indicates that the water molecule in [AA-(H(2)O)(1)](+) migrates from the CO group to the NH group in the D(0) state. The reorganization of the charge distribution from the neutral to the D(0) state of AA induces the repulsive force between the water molecule and the CO group of AA(+), which is the trigger of the water migration in [AA-(H(2)O)(1)](+).
authors.affiliation: Department of Chemistry, Faculty of Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakota
authors.forename: Satoshi
authors.initials: S
authors.lastname: Harada
authors.forename: Yuiga
authors.initials: Y
authors.lastname: Shimazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekiya
mesh_terms: D000083:Acetanilides / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D016000:Cluster Analysis; D005740:Gases / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D013055:Spectrophotometry, Infrared / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D000083:Acetanilides; D000577:Amides; D002412:Cations; D005740:Gases; D014867:Water; C508827:acetanilide