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Exciton Reflection Spectra of NaI Crystals. Effect of Surface Irradiation by Photons and Incidence Angle Dependence
Author(s) -
O'ConnelBronin A. A.,
Treshchalov A. B.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221620126
Subject(s) - exciton , spectral line , atomic physics , reflection (computer programming) , angle of incidence (optics) , crystal (programming language) , resonance (particle physics) , dispersion (optics) , photon , line (geometry) , physics , irradiation , molecular physics , chemistry , optics , condensed matter physics , nuclear physics , astronomy , computer science , geometry , mathematics , programming language
Reflection spectra of NaI crystals cleaved in liquid helium are investigated in detail. A fine structure is discovered in the spectral region adjacent to 2S exciton resonance at the high‐energy side. It is interpreted as the manifestation of the splitting of the n = 2 exciton state which was predicted by Balslev. The LO structure below the 2S line is observed, which is interpreted as the revealing of vibrational states of self‐trapped excitons. The influence of irradiation by photons on the crystal surface is studied. Considerable changes are detected in the 2S reflection line region, which are discussed involving the “dead” layer model. The character of the dispersion contour of the 2S exciton line is discussed. The dependence of the reflection spectrum on the incidence angle is investigated. A stronger angular dependence in the 2S region of the spectrum than in the 1S region is pointed out.