Dynamical Jahn-Teller effects in the near ultraviolet vapor phase absorption spectra of perrhenyl chloride, ReO 3Cl, and pertechnyl chloride, TcO 3Cl
The near ultraviolet vapor phase absorption spectra of perrhenyl chloride and pertechnyl chloride have been observed over a range of vapor pressures and path lengths. There are several similarities in the overall features of the spectra for the two molecules. Each spectrum shows evidence of two electronic transitions at wavelengths greater than 2000 Å; the longer wave-length band system of each spectrum exhibits vibrational structure with an irregular spacing of the order of 800-900 cm -1. This band system is assigned as an E ← A1 electronic transition with progressions in ν4'. This vibration is coupled to the electronic motion to produce a dynamical Jahn-Teller effect. Calculations of the geometry in the excited state show that there is an asymmetric distortion in the metal-oxygen bond lengths.