Some studies in the spectra of single uranyl halides and other uranyl salts

Summary

The fluorescence spectra at liquid-air temperature of crystalline uranyl chloride, uranyl fluoride I and II, and of uranyl bromide have been studied for the first time. The spectra of uranyl acetate, nitrate, sulphate and uranyl potassium sulphate have been taken for comparison. Out of the several series present, B, C, D and E are pointed out to be most important. A remarkable shifting of the D band as well as peculiarities in the intensity distribution are noticeable. The similarity between the C and E bands and the extended diffuseness produced by the D bands are also noteworthy.

A slight rise in temperature from −185°C. causes a great increase in the diffuseness produced by the D bands. With moist crystals the D band appears as a short continuum even at −185° C. but at −110° C. and −70°C. only B, C and E are present, the D bands completely disappear. Uranyl bromide has been found to increase tremendously in intensity on cooling, its spectrum at −185° consisting of very broad bands giving an appearance of a continuous spectrum.

The absorption spectra of uranyl chloride have been taken with varying thickness of the absorbing layer. With thick layers, some bands which are observed in fluorescence can also be obtained in absorption. In the absorption spectrum of uranyl fluoride II and uranyl bromide the first two A and B bands of the fluorescence spectra appear as A and B band in absorption with a remarkable reversal of intensity.