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Directional Dependence of Extraordinary Infrared Oscillator Parameters of Uniaxial Crystals (I)
Author(s) -
Merten L.,
Lamprecht G.
Publication year - 1970
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.19700390225
Subject(s) - dispersion relation , attenuation , orientation (vector space) , dispersion (optics) , physics , infrared , lattice (music) , quartz , dielectric , optics , condensed matter physics , mathematical analysis , quantum mechanics , materials science , mathematics , geometry , acoustics , composite material
The validity of the classical dispersion relation (resonance terms of Lorentzian type) for the reststrahlen range of the extraordinary ir spectrum may also be rigorously verified from the basic equations of lattice dynamics combined with the Maxwell equations. The parameters occurring in the dispersion equations, viz. ϵ ∞ (ϑ) (high‐frequency dielectric constant), ω j (ϑ) (dispersion frequencies), 4πϱ j (oscillator strengths), and γ j (ϑ) (attenuation constants), become however orientation dependent, where ϑ is the angle between wave vector and optical axis. Explicit formulae may be given for the orientation dependence of these parameters. As an example the orientation dependence, especially of the oscillator strengths (neglecting attenuation) of α‐quartz, are calculated numerically and discussed in detail. Recently Onstott and Lucovsky have been investigated experimentally the orientation dependence of oscillator strengths of α‐quartz for two of the branches systematically. In consideration of a first comparison the agreement with the values calculated is very satisfactory.