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Directional dispersion of polar phonons measured by infrared reflection
Author(s) -
Falge H. J.,
Schuller E.,
Borstel G.
Publication year - 1976
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.2220780110
Subject(s) - phonon , polar , surface phonon , polariton , condensed matter physics , dispersion (optics) , optics , reflection (computer programming) , raman spectroscopy , crystal (programming language) , dispersion relation , uniaxial crystal , materials science , transverse plane , physics , optical axis , quantum mechanics , structural engineering , engineering , lens (geology) , computer science , programming language
The dispersion of all polar optical phonons may be measured by the attenuated total reflection method. It is shown how the directional dispersion of the extraordinary polar phonons in uniaxial crystals is obtained in a similar way. In the (ω, k ) diagram the areas of high reflectivity for transverse magnetic polarized incident radiation are determined by curves which have for k → 0 the same frequencies as extraordinary phonons propagating in an infinite crystal for k → ∞. At arbitrary crystal cuts these curves are boundaries for the existence of surface phonon‐polaritons. The method allows measuring the complete directional dispersion of t—t and l—l branches of Raman‐inactive polar phonons, too.