Experimental investigation of the Jahn-Teller effect in the ground and excited electronic states of the tropyl radical. Part II. Vibrational analysis of the (A)over-tilde(2)E(3)''-(X)over-tilde(2)E(2)'' electronic transition

摘要

Laser-induced fluorescence (LIF) and laser-excited dispersed fluorescence (LEDF) spectra of the cycloheptatrienyl (tropyl) radical C7H7 have been observed under supersonic jet-cooling conditions. Assignment of the LIF excitation spectrum yields detailed information about the (A) over tilde -state vibronic structure. The LEDF emission was collected by pumping different vibronic bands of the (A) over tilde E-2(3 '') <-(X) over tilde E-2(2)'' electronic spectrum. Analysis of the LEDF spectra yields valuable information about the vibronic levels of the (X) over tilde E-2(2)'' state. The (X) over tilde and (A) over tilde -state vibronic structures characterize the Jahn-Teller distortion of the respective potential energy surfaces. A thorough analysis reveals observable Jahn-Teller activity in three of the four e(3)' modes for the (X) over tilde E-2(2)'' state and two of the three e(1)' modes for the (A) over tilde E-2(3)" state and provides values for their deperturbed vibrational frequencies as well as linear Jahn-Teller coupling constants. The molecular parameters characterizing the Jahn-Tellei interaction in the (X) over tilde and (A) over tilde states of C7H7 are compared to theoretical results and to those previously obtained for C5H5 and C6H6+. (c) 2008 American Institute of Physics.