Effect of Pressure on the Spectra of Crystalline UF4 and UF3

Abstract

The effect of pressure has been measured on the crystalline spectra of UF₄ and UF₃. The UF₃, which has a structure analogous to PrF₃ and NdF₃, behaved much like those compounds, showing a 15% to 40% increase in intensity for different peaks in 50 000 atm. In UF₄ certain of the peaks increased in intensity while others decreased. The U⁴⁺ ion is almost at a center of symmetry in this crystal. It is indicated that the intensity behavior is reasonable if a significant fraction of the intensity is obtained due to lattice vibrations. Both red and blue shifts are observed on different peaks.