Theoretical analysis of optical spectra of uranyl in complexes

A theoretical model is developed for simulating optical spectra of uranyl in complexes. The spectral profiles of electronic and vibronic transitions of UO 2 2 + bonded to equatorial ligands are evaluated based on the Huang–Rhys theory of vibronic coupling in solids. This model assumes that only the symmetric OUO stretching mode exhibits multi-phonon progression, whereas all other local modes are not Franck–Condon allowed and treated as false origins of the progressing mode. A simulation of vibronic transitions in the UO2(NO3)2(TBP)2 complex is compared with absorption spectrum to determine the excited state energy levels, frequencies of local vibration modes and vibronic coupling strength.