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Series

Ames Laboratory

1972

Articles 1 - 4 of 4

Full-Text Articles in Physics

Low-Energy Optical Absorption In Reo3, J. H. Weaver, David W. Lynch Nov 1972

Low-Energy Optical Absorption In Reo3, J. H. Weaver, David W. Lynch

Physics and Astronomy Publications

The absorptivity of polycrystalline samples of ReO3 has been measured in the range 0.11 to 2.8 eV using a calorimetric technique. New structures have been found in the absorptivity, appearing at about 0.4 and 1.0 eV. The data have been Kramers-Kronig analyzed to obtain the optical constants. Band-calculation results of Mattheiss are presented and a tentative identification of the origin of the new structures is made. A comparison of the present data with those of Feinleib, Scouler, and Ferretti is made.


Thermomodulation Spectra Of Al, Au, And Cu, R. Rosei, David W. Lynch May 1972

Thermomodulation Spectra Of Al, Au, And Cu, R. Rosei, David W. Lynch

Physics and Astronomy Publications

Thermotransmission and thermoreflection measurements were made on semitransparent films of Al, Au, and Cu at about 370 and 120 K in the range 0.5-5 eV. The data yield the thermomodulation spectrum Δε2 of the imaginary part of the dielectric constant directly, without Kramers-Kronig analysis. A comparison of the interband region of Δε2 for Cu with the piezo-modulation spectrum of a single crystal shows that broadening of the Fermi distribution and volume strain caused by thermal expansion are the principal causes of the Δε2 spectrum. The Δε2 spectrum for Al is particularly simple and can be discussed using closed-form expressions ...


Optical Properties Of Single-Crystal Zinc, J. H. Weaver, David W. Lynch, R. Rosei Apr 1972

Optical Properties Of Single-Crystal Zinc, J. H. Weaver, David W. Lynch, R. Rosei

Physics and Astronomy Publications

Measurements were made of the absorptivity of single crystals of zinc from 0.1 to 3.0 eV at 4.2K. Polarized radiation was used with the electric field vector parallel or perpendicular to the c axis of the crystal. New structure was found for E⃗ ⊥c^at about 0.15 eV; no low-energy structure was observed for E⃗ ∥c^. The low-energy interband transition is attributed to transitions near the point K in the Brillouin zone. The structure in the near-infrared and visible spectra is highly temperature dependent. Comparisons of the absorptivity and the conductivity are made between our 4 ...


Deformation Potentials For Excitons In Cuprous Halides, J. B. Anthony, A. D. Brothers, David W. Lynch Apr 1972

Deformation Potentials For Excitons In Cuprous Halides, J. B. Anthony, A. D. Brothers, David W. Lynch

Physics and Astronomy Publications

The hydrostatic-pressure shifts of the Z1,2 and Z3 exciton peaks were measured in thin films of cubic CuCl, CuBr, and CuI at 90 K. That of the E1 peak in CuI also was measured. The deformation potentials of all Z excitons and of the E1exciton in CuI, about -1 eV, are more than twice those of the Z excitons in CuCl and CuBr. This suggests the two valence bands in CuI may be considerably more mixed than in CuCl and CuBr.