Photodissociation spectroscopy of benzene cluster ions in ultraviolet and infrared regions: Static and dynamic behavior of positive charge in cluster ions

摘要

Photodissociation spectroscopy is applied to benzene cluster ions in ultraviolet and infrared regions. In the ultraviolet photodissociation spectrum of (C6H6); , a characteristic broad band emerges at 255 nm. This band is assigned to a 7T* f- 7T transition of a solvent benzene molecule that exists in the trimmer. This is in accordance with the previous model of the ion cluster with a dimmer ion core and a solvent benzene molecule. The infrared photodissociation spectra of (C6H6) ; ( n = 3- 5) show a sharp band at 3066 cm-l. The band is attributed to a C-H stretching vibration of thediller ion core. The infrared spectra of ( C6H6); ( n = 3- 5) are fitted to the model spectra reproduced by combining the C-H stretching bands of the dimmer ion core and the solventbenzene molecule. The infrared photodissociation spectra of mixed benzene triller ions with one or two benzene-d6 molecules demonstrate that there is no correlation between the excited dimmer ion core site in the triller and the photofiagment dimmer ion species. This implies that a dimmer ion core switching occurs in photoexcited vibrational states prior to the dissociation.