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Journal of Physical Studies 21(1/2), Article 1801 [5 pages] (2017)
DOI: https://doi.org/10.30970/jps.21.1801 AN EXPERIMENTAL STUDY AND QUANTUM-CHEMICAL CALCULATIONS OF SPECTRAL AND LUMINESCENCE PROPERTIES OF PROLINE MOLECULESM. I. Myhovich, V. A. Kelman
Institute of Electron Physics, National Academy of Sciences of Ukraine, |
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The spectra of photoluminescence of the proline molecule in the powder state and the aqueous solution one, excited by the action of irradiation $\lambda=253$\,nm of Ti: sapphire laser, were investigated and analyzed. The spectrum of photoluminescence of the aqueous solution revealed a greater spectral width and a long-wave shift of the main maximum of radiation compared with the spectra of photoluminescence of the powder, which is due to the influence of the solvent on the molecule of the proline. Finding the abscissa of the intersection point of the longwave edge of the absorption curve also measured in a spectral range of 200-350 nm, and the short-wave edge of the photoluminescence curve, the energy of the first excited singlet state of the proline molecule was determined as $-3.9$\,eV.
Using the methods of quantum chemistry, electronic absorption spectra of the proline molecule are calculated, which are well matched with experimental data. It is established that the long-wave absorption band, which is responsible for the first excited singlet state, is mainly due to transitions from the higher occupied molecular orbital to the lower unoccupied molecular orbital. In aggregate, these data determine the detailed composition of the absorption bands and their origin. Also, a dipole momentum, and atomic distribution of charges of a molecule of proline, are calculated. A comparison of experimental data with theory is drawn. A low level of quantum exit of luminiscence was found.
PACS number(s): 87.15.mq