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Series

Ames Laboratory

1988

Atomic, Molecular and Optical Physics

Articles 1 - 3 of 3

Full-Text Articles in Physics

Ellipsometric Study Of Optical Transitions In Ag1−Xinx Alloys, Kwang-Joo Kim, Liang-Yao Chen, David W. Lynch Dec 1988

Ellipsometric Study Of Optical Transitions In Ag1−Xinx Alloys, Kwang-Joo Kim, Liang-Yao Chen, David W. Lynch

Physics and Astronomy Publications

The dielectric functions of disordered Ag1−xInx alloys (x≤0.12) were obtained ellipsometrically in the 1.25.5-eV energy region. In the low-energy region, the intraband scattering rate, described by τ−1=τ−10+βω2, increases with increasing In concentration. The increasing positive values of β with increasing In content do not agree with a calculation based on the assumption of a spherical Fermi surface and isotropic scattering from an impurity represented by a screened Coulomb potential. The onset energy of the L3→L’2(EF) transition, 4.03 eV for pure Ag, shifts to higher energies, while ...


Ellipsometric Studies Of Magnetic Phase Transitions Of Fe-Rh Alloys, Liang-Yao Chen, David W. Lynch Jun 1988

Ellipsometric Studies Of Magnetic Phase Transitions Of Fe-Rh Alloys, Liang-Yao Chen, David W. Lynch

Physics and Astronomy Publications

Spectroscopic ellipsometric measurements of the dielectric functions for Fe-Rh alloys with 48, 50, 52, and 54 at. % Fe concentrations were performed between 25 and 125 °C in the 13-eV range. Results show that the band structure of Fe-Rh is not drastically affected as the antiferromagnetic-ferromagnetic phase transition occurs and is less affected than band-structure calculations indicate. Therefore, the large change in the linear term of the electronic specific heat between the antiferromagnetic and ferromagnetic phases can be attributed primarily to a magnetic contribution rather than to a change in the density of electronic states at the Fermi surface.


Empirical Band Calculations Of The Optical Properties Of D-Band Metals. Vi. The Optical Conductivity Of Ferromagnetic Iron, J. H. Sexton, David W. Lynch, R. L. Benbow, N. V. Smith Feb 1988

Empirical Band Calculations Of The Optical Properties Of D-Band Metals. Vi. The Optical Conductivity Of Ferromagnetic Iron, J. H. Sexton, David W. Lynch, R. L. Benbow, N. V. Smith

Physics and Astronomy Publications

The optical conductivity of ferromagnetic Fe was calculated with an interpolation scheme fit to first-principles energy bands for paramagnetic Fe with a constant exchange splitting. Most of the contributions to the conductivity originate in the minority-spin bands, making the rigid splitting a valid assumption. The inclusion of electric-dipole matrix elements is essential for obtaining agreement with experiment. The locations of the transitions in the band structure were found by plotting contributions from differential volumes throughout the irreducible wedge of the Brillouin zone, including dipole matrix elements. The strong transitions around 2.5 eV occur between flat bands in large regions ...