New insight into UO2F2 particulate structure by micro-Raman spectroscopy

Uranyl fluoride particles produced via hydrolysis of uranium hexafluoride have been deposited on different substrates: polished graphite disks, silver foil, stainless steel and gold-coated silicon wafer, and measured with micro-Raman spectroscopy (MRS). All three metallic substrates enhanced the Raman signal delivered by UO2F2 in comparison to graphite. The fundamental stretching of the U–O band appeared at 867 cm−1 in case of the graphite substrate, while in case of the others it was shifted to lower frequencies (down to 839 cm−1). All applied metallic substrates showed the expected effect of Raman signal enhancement; however the gold layer appeared to be most effective. Application of new substrates provides more information on the molecular structure of uranyl fluoride precipitation, which is interesting for nuclear safeguards and nuclear environmental analysis.

► Uranyl fluoride particles prepared via hydrolysis of UF6 were deposited on metallic substrates for micro-Raman spectroscopy.
► New substrates enhanced Raman signal from the particles of the size below 1 μm.
► Raman shift of U-O symmetric stretching appeared at values 847/842/839 cm−1 due to gradual water absorption by UO2F2.
► The smooth substrates facilitated the process of water saturation of deposited particulate uranyl fluoride.
► UO2F2 particles deposited of metallic surfaces appeared very stable under long-term exposure of a laser beam.