Raman spectroscopic investigation of UCl4

Uranium chloride salts are a proposed fuel source for molten salt reactors (MSRs). However, despite their relevance to nuclear energy, they remain understudied, in part because of their air and moisture sensitivity. This work provides the first Raman spectra of UCl₄ from 45 to 3200 cm⁻¹ collected with 532 and 785 nm excitation sources as well as the assignment of 10 identified peaks to their respective vibrational modes. These Raman bands are compared to those for isostructural ThCl₄, the compositionally related UCl₃, and the computed Raman bands for UCl₄ from local vibrational mode analysis. The observed spectrum of UCl₄ is in accord with that of ThCl₄ and the computed spectra of UCl₄. We posit that the observed differences between the spectra of UCl₄ and UCl₃ are useful in differentiating these species for applications such as in situ monitoring of MSR operations.