Electronic absorption spectra of carboxamides

Luminescence centres in dried urine samples containing urate and oxalate salts

“…The studies of electronic spectra of some carbamides by means of electron spectroscopy and quantum chemistry aimed at elucidating their long-wave absorption have been presented in [11], along with the appropriate interpretation of its nature in connection with the urea molecule. In the work [12] the long-wave absorption band peaked approximately at 5.4 eV (230 nm) has been measured accurately and related to an n-π*-transition.…”

“…Again, a "blue shift" of this band detected with increasing solvent polarity could be caused by the same n-π*-transition. Since just this effect has been observed when some mineral acids are added to the urea solution, one can surely interpret the transition near 5.4 eV as the n-π*-transition [11]. Analysis of the absorption spectra of urea and calculations of its electronic structure according to the Hukel's method has been performed in the study [13].…”