Trapped hydronium radical produced by UV excitation of substituted aromatic molecule

F. HERNÁNDEZ; M. C. CAPELLO; A. NAITO; S. MANITA; K. TSUKADA; M. MIYAZAKI; M. FUJII; M. BROQUIER; G. GRÉGOIRE; C. DEDONDER-LARDEUX; C. JOUVET; G. A. PINO *

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015 vol. 119 p. 12730 - 12735

1089-5639

The gas phase structure and excited state dynamics of o-aminophenol-H2Ocomplex have been investigated using REMPI, IR-UV hole-burning spectroscopy, and pump−probe experiments with picoseconds laser pulses. The IR-UV spectroscopy indicates that theisomer responsible for the excitation spectrum corresponds to an orientation of the OH bondaway from the NH2 group. The water molecule acts as H-bond acceptor of the OH group of thechromophore. The complexation of o-aminophenol with one water molecule induced anenhancement in the excited state lifetime on the band origin. The variation of the excited statelifetime of the complex with the excess energy from 1.4 ± 0.1 ns for the 0−0 band to 0.24 ± 0.3ns for the band at 0−0 + 120 cm−1 is very similar to the variation observed in the phenol-NH3system. This experimental result suggests that the excited state hydrogen transfer reaction is thedominant channel for the non radiative pathway. Indeed, excited state ab initio calculationsdemonstrate that H transfer leading to the formation of the H3O? radical within the complex is the main reactive pathway.