The Contours of the Bands of the Structural Luminescence and Absorption Spectra of Solid Solutions and Crystals of Uranyl Compounds at Low Temperatures

Temperature evolution of the fine structure of the electronic spectra of uranyl nitrates and fluorides is considered. It is shown that for pure crystals at T = 4.2 K the contour is described by the Lorentz curve; for other cases a convolution of the type of the Voigt function is typical. Weak electron–phonon interaction leads to temperature broadening of spectra predominantly due to the Boltzmann change in the population of the initial electronic–vibrational states.