Accession Number : AD0704551

Title :   CHARACTERISTIC ENERGY ABSORPTION SPECTRA OF SOLIDS.

Descriptive Note : Physical sciences research papers,

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : Plendl,Johannes N.

Report Date : AUG 1969

Pagination or Media Count : 85

Abstract : A method was developed to derive the fundamental absorption spectra of solids directly from experimental infrared data without having to resort to computational evaluation. These characteristic lattice absorption spectra represent the true energy absorption spectra of solids and are, through Kirchhoff's Law, directly related to the emission spectra of solids. As opposed to the traditional absorption coefficient (k) versus frequency curve, which is regarded as the absorption spectrum for solids in the region of anomalous dispersion, the spectra, as derived by the proposed method, clearly resolve the transverse and longitudinal modes of vibration. They also exhibit the characteristics of anharmonicity and damping. The method uses the combined reflection and transmission data on single-crystal and thin-film specimens. Its validity has been verified on a wide variety of solids. The most recent data obtained from emission, laser-Raman, or cold neutron scattering techniques, is in complete agreement with the derived values. A method of calculating the various modes of vibration of solids, directly from elastic constants, is also advanced. The importance of these spectra is discussed with regard to problems in solid state physics (particularly damping characteristics, temperature effects, and nonlinear effects of atomic binding in solids). (Author)

Descriptors :   (*SOLIDS, *INFRARED SPECTRA), (*RAMAN SPECTROSCOPY, SOLIDS), CRYSTAL LATTICES, SCATTERING, FILMS, SINGLE CRYSTALS, VIBRATION, ALKALI METAL COMPOUNDS, COPPER COMPOUNDS, HALIDES, NEUTRON SCATTERING, CHEMICAL BONDS, ABSORPTION SPECTRA

Subject Categories : Atomic and Molecular Physics and Spectroscopy
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE