LUMINESCENCE OF URACIL ON THE CERAMICS SURFACE AT ELECTRONIC EXCITATION

Abstract

The method of electron-photon spectroscopy was applied to an important class of six-membered heterocyclic compounds-pyrimidine nitrogen bases, which are part of nucleic acids. Excited by electron bombarding with energy of 600 eV in a high vacuum, luminescence spectrum of uracil molecules adsorbed on the ceramic surface was analyzed. Broad bands with maxima at 335, 435, and 495 nm were found in the UV and visible regions. The most intense band (l = 335 nm) is related to fluorescence and corresponds to the singlet-singlet transition from the first excited electronic state to the ground state of the molecule. Less intense phosphorescence band (l = 435 nm) is formed by electron transitions from the triplet Т₁ to the ground state. The nature of the band with a maximum of 495 nm is discussed. The obtained luminescence spectrum is compared with the photoluminescence spectra in different phase states.