Knowledge Bank

Laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the cycloheptatrienyl (tropyl) radical (C$7$H$7$) have been observed under supersonic jet cooling conditions. The DF emission was collected by pumping different vibronic bands of the $A~2$EE LIF excitation spectrum. Analysis of the DF spectra yields valuable information about the vibrational levels of the ground $X~2$E electronic state. In addition to the experimental work, \textit{ab initio} calculations have been performed providing ground and excited state Jahn-Teller parameters; a comprehensive analysis reveals Jahn-Teller activity in 4 $e3\prime$ modes for the $X~2$E state and 3 $e1\prime$ modes for the $A~2$E and provides values for their vibrational frequencies as well as linear Jahn-Teller constants. In addition to the magnitude of the Jahn-Teller distortion, the stabilization energies for both electronic states have been calculated at the CASSCF(7,7) and EOMEA-CCSD levels of theory using different basis sets.