INTENSITY DISTRIBUTION IN THE PROGRESSIONS OF VIBRONIC TRANSITIONS OF METAL-ION COMPLEXES

The intensity distribution of the vibrational progressions t1u+na1g and t2u+ na1g in a vibronically induced transition has been investigated using ReC162- doped in Rb2TeCl6 and Cs2TeCl6 as an example. It has been shown that this distribution can be expressed in condensed form by an intramolecular distribution function I0 (n, Δr, βr) where n denotes the member in the progression and Δr and βr represent changes in equilibrium position and frequency, respectively, of the mode Г following an electronic transition. For Rb2TeCl6: Re4+ the experimental data are best fitted to the theory with the parameters Δ = 0.37 and β = 0.995, and for Cs2TeCl6: Re4+ Δ = 0.32 and β = 0.995. The A-parameters correspond to a change in the nuclear equilibrium configuration of the metal-ligand distances by 0.015-0.020 Å on excitation of the molecule to2T2g. The detection of an eg vibronic line and its combinations eg + na1g is explained by a Jahn-Teller distortion in the4T2g excited state. © 1979 Taylor & Francis Group, LLC.