Luminescence centres in dried urine samples containing urate and oxalate salts

Abstract

Photoexcitation and luminescence spectra of urea and dried urine samples are studied. The obtained spectra are deconvolved into elemental components by means of Alentsev-Fock's technique. The luminescence bands of the urea and the dried urine samples with the maxima located near 2.2 and 2.64 eV are shown to be caused by n→π*-transition of non-bonding electrons in heteroatoms O and N. The luminescence bands of the urea and the urine with urate salts reveals the maximum near 3.64 eV, which is caused by n→σ*-transition associated with redistribution of electron density in the carbonyl group. The luminescence band with the maximum near 1.85 eV is linked to the luminescence of urate salts in pathological urine.

Effects of impurity band in heavily doped ZnO:HCl

“…The near band-gap PL spectrum decomposed by means of Alentsev method, using varied excitation levels, is shown in Fig. 1(a, b) [22,23]. The short-wavelength band F XA at 3.366 eV (368.4 nm) almost coincides with the free exciton band [1].…”