Photoinduced Rydberg ionization spectroscopy of the B state of benzonitrile cation.

Photoinduced Rydberg ionization (PIRI) spectra of the second excited electronic state of benzonitrile cation were recorded via the origin and 6a¹ and 6b¹ vibrational levels of the cation ground electronic state. This B←X transition was verified to be a forbidden ²B₂←²B₁ transition with an origin at 17 225 cm^-1 above the ground ionic state. By the use of vibronic coupling calculations, as well as symmetry analysis and comparison of the PIRI spectra via different ground vibrational levels, a nearly complete assignment of the vibrational structure was made, and the vibrational frequencies of the B ²B₂ state of benzonitrile cation were obtained based on the assignments. Comparisons of the experimental spectra with simulations from the vibronic structure calculations are also used to validate the theoretical procedures used in the simulations. [ABSTRACT FROM AUTHOR]