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Series

Ames Laboratory

1970

Articles 1 - 4 of 4

Full-Text Articles in Physics

Optical Properties Of Antiferromagnetic Chromium And Dilute Cr-Mn And Cr-Re Alloys, Laurence W. Bos, David W. Lynch Dec 1970

Optical Properties Of Antiferromagnetic Chromium And Dilute Cr-Mn And Cr-Re Alloys, Laurence W. Bos, David W. Lynch

Physics and Astronomy Publications

The antiferromagnetic energy gap and optical properties of single crystals of Cr and of Cr alloyed with 0.45, 0.94, 2.5, and 4.5% Mn and with 1.05 and 2.0% Re have been investigated by measuring the optical absorption over a photon energy range of 0.08-5 eV. The data were taken at 4.2 K by a calorimetric technique. It is found that at 4.2 K, approximately 1% Mn or Re will cause commensurate antiferromagnetic ordering, and the energy gap shifts abruptly from 0.13 to 0.36 eV near this concentration of diluent ...


Optical Properties Of The Rubidium And Cesium Halides In The Extreme Ultraviolet, M. Cardona, R. Haensel, David W. Lynch, B. Sonntag Aug 1970

Optical Properties Of The Rubidium And Cesium Halides In The Extreme Ultraviolet, M. Cardona, R. Haensel, David W. Lynch, B. Sonntag

Physics and Astronomy Publications

The absorption spectra of evaporated thin films of all rubidium and cesium halides in the 50- to 250-eV region are reported. In this range, transitions from the 3d shell of Rb+ and from the 4d and 4p shells of Cs+ can be seen, as well as some transitions from inner shells of the halogen ions. Besides the absorption fine structure near the threshold for inner-shell transitions, broad absorption structure is observed and explained as due to d→f continuum transitions. The number of effective electrons whose oscillator strength has been exhausted in our spectral region has been computed from the ...


Low-Energy Optical Absorption Peak In Aluminum And Al-Mg Alloys, L. W. Bos, David W. Lynch Jul 1970

Low-Energy Optical Absorption Peak In Aluminum And Al-Mg Alloys, L. W. Bos, David W. Lynch

Physics and Astronomy Publications

Measurements of the absorptivity of Al and dilute Al-Mg alloys were made at 4.2 K in the 0.2- to 5-eV energy region by a calorimetric technique. In addition to the well-known conductivity peak around 1.6 eV, another peak has been found near 0.5 eV. These peaks are present in the alloys, broadened, but unshifted, as well as in Al. The peaks are at about 2|V200|and 2|V111|, respectively, where the V's are Fourier coefficients of the pseudopotential.


Pressure Shift Of The U Band In Kbr, A. D. Brothers, David W. Lynch, C. G. Olson Feb 1970

Pressure Shift Of The U Band In Kbr, A. D. Brothers, David W. Lynch, C. G. Olson

Physics and Astronomy Publications

The pressure derivative of the U-band peak position in KBr was determined to be +27×10−6 eV bar−1 and +30×10−6eV bar−1 for H− and D− impurities, respectively. These are equal, within the uncertainty of ±3×10−6 eV bar−1 for each coefficient. The shift of the peak of the U band with temperature is shown to arise almost entirely from thermal expansion.