The resonance Raman effect of dicaesium uranyl tetrachloride in dimethyl sulfoxide

Abstract

The resonance Raman scattering spectra of dicaesium uranyl tetrachloride (Cs 2UO 2Cl 4) in dimethyl sulfoxide ((CH 3) 2SO) have been measured under laser excitation of the uranyl ion in resonance with the 1Σ g +→ 1Φ g Laport-forbidden f– f electronic transitions (520–450 nm) by using 10 output lines of the argon-ion laser at room temperature. The excitation profile of the totally symmetric stretching vibrational mode of uranyl observed at 830 cm −1 is presented and analyzed in terms of the transform methods which are able to formally bypass multimode complexities. The non-Condon model (generalized B, C-terms of scattering) gives a relatively good agreement with the resonance excitation profile of experiment. Reliable value of the nuclear displacement on going the 1Σ g +→ 1Φ g electronic transition and the amount of charge transferred from the ligand to uranium of uranyl ion both in the ground and excited states are obtained. It is found that the average number of ligands coordinated equatorically to the central uranium atom affects on the amount of charge transferred from the ligand to uranium, especially in the electronic excited state. As increasing the average number of ligands, the amount of charge transferred from the ligand to uranium increases in the ground state, while in the electronic excited state, the charge transferred decreases.