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The influence of spatial dispersion and of the angle of incidence on thermomodulation spectra of the A n=1 ‐exciton in CdS
Author(s) -
Stössel W.,
Wagner H. J.
Publication year - 1979
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.2220960139
Subject(s) - exciton , transverse plane , spectral line , reflection (computer programming) , dispersion (optics) , reflectivity , spatial dispersion , thermal , angle of incidence (optics) , optics , molecular physics , materials science , dispersion relation , condensed matter physics , physics , quantum mechanics , thermodynamics , structural engineering , computer science , engineering , programming language
Relflectance ( R ) and thermomodulated reflectance spectra (Δ R / R ) of CdS in the region of the A n=1 ‐exciton are measured at 8 K for angles of incidence between 5° and 85°. Because of the higher resolution obtained with the thermomodulation technique, a different behaviour of the “spike”, i.e. the additional reflection structure due to spatial dispersion, is detected than that previously derived from reflectance measurements alone. Measurements of its temperature dependence show that the spike is not very sensitive to thermal broadening. Fitting calculations, made with Pekar's additional boundary condition and allowing for an exciton‐free surface layer, show that the underlying models describe very well the experimental data, namely the behaviour of the transverse and the longitudinal exciton modes as well as that of the longitudinal‐transverse mixed mode.