High resolution spectroscopy of several rovibronically excited bands of 5-cyanoindole – The effect of vibrational averaging

The rovibronic spectra of two bands of 5-cyanoindole at 348 and 884 cm−1 have been measured and analyzed using a rigid rotor Hamiltonian. A vibrational assignment could be given on the basis of an anharmonic analysis of the vibrational spectrum of 5-cyanoindole making use of the information of the vibrationally averaged rotational constants. Strong vibronic mixing to a higher lying electronically excited state has been found.