APPLICATIONS OF 2-PHOTON SPECTROSCOPY TO INORGANIC-COMPOUNDS .1. SPECTRUM AND ELECTRONIC-STRUCTURE OF CS2UO2CL4

The single-crystal polarized two-photon absorption spectrum of Cs2UO2Cl4 at 4.2 K is reported. The spectrum is much more highly resolved than the single-photon spectrum and clearly reveals the electronic origin transitions for 13 of the 14 excited states present in the region below 33 000 cm–1. The frequencies of a number of gerade excited-state vibrational modes are readily determined and indicate a very small change in the charge distribution within the UO22+ ion accompanying the excitation. The strong coupling of the rocking mode of this ion is also apparent. The two-photon polarization data confirm the symmetries of the states and demonstrate that, in some cases, the vibronic intensity arises from interactions in the virtual state coupled by the radiation field. The sign of the tetragonal field splitting is not consistent with the predictions of recent ab initio calculations. © 1987, American Chemical Society. All rights reserved.