Time- and frequency-resolved photoionization of the C A22 state of the benzyl radical, C7 H7

Abstract

The structure and dynamics of the C A22 electronically excited state of the benzyl radical, C7 H7, were investigated by nanosecond and femtosecond pump-probe photoionization. A free jet of benzyl radicals was generated by flash pyrolysis from the precursors 2-phenylethyl nitrite and toluene. Nanosecond multiphoton ionization spectra show a number of vibronic bands that are excited in the wavelength range of 290-310 nm. At excitation wavelengths of 305, 301, and 298 nm, rapid biexponential decay of the excited states was observed. Lifetimes at the C-state origin (305 nm excitation) are 400 fs and 4.5 ps. The lifetimes decrease with increasing excitation energy. The dynamics can be understood within a two-step internal conversion to the electronic ground state. © 2010 American Institute of Physics.