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Current issue   Ukr. J. Phys. 2014, Vol. 59, N 3, p.209-214

    Paper

Curmei N.D., Klishevich G.V., Melnyk V.I.

Institute of Physics, Nat. Acad. of Sci. of Ukraine
(46, Nauky Av., Kyiv 03028, Ukraine; e-mail: Curmei_ND@ukr.net)

Low-Temperature Electron Spectra of Impurities in Naphtalene Crystals

Section: Atoms and molecules
Original Author's Text: English

Abstract: This work relates to the study of vibrational structures in the electron spectra of naphthalene crystals with impurities of β- and α-naphthalene fluorine with concentrations of 10−4 to 10 wt.% at a temperature at 4.2 K. It is determined that, at low impurity concentrations, the spectra have a doublet structure and consist of narrow quasilines with initial values of ν01 = 31322 cm−1 and ν02 = 31226 cm−1 , which are resonance-coincident in the absorption and fluorescence spectra. It is demonstrated that if the impurity concentration increases, the series of narrow quasilines appear in the areas of the 0-0 transitions of the impurity centers of both types together with the doublet structure. A part of these quasilines is polarized predominantly along the b-axis of a naphthalene crystal. The model is proposed for impurity centers, which induce the generation of new spectral bands. This model is based on the interaction of translation-nonequivalent impurity molecules in the elementary lattice cell of a naphthalene crystal. At high impurity concentrations, the resonance-symmetric wide spectral bands appear in the absorption and fluorescence spectra. The analysis of the results obtained is performed with consideration for the Franck–Condon interaction and the Herzberg–Teller interaction.

Key words: vibrational structure, absorption and fluorescence spectra, β- and α-naphthalene fluorine, impurity center.