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19 results on '"Jassemnejad B"'

1. Manganese absorption in CaF2:Mn; I.

Author

McKeever, S. W. S., Jassemnejad, B., Landreth, J. F., and Brown, M. D.

Subjects
*SPECTRUM analysis, *MANGANESE spectra, *CALCIUM fluoride
Abstract

Focuses on a study which examined optical absorption spectra for manganese in CaF[sub2]. Experimental procedures; Results; Discussion; Summary.

Published
1986
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9. Energy transfer in CaF2:Ce, Mn

Author

McKeever, S. W. S., Jassemnejad, B., Brown, M. D., Mathur, V. K., Abbundi, R. J., and Chan, H.

Abstract

Crystals of CaF2 containing different concentrations of Ce3+ and Mn2+ ions were investigated by means of optical absorption and photoluminescence. The results suggest the preferential pairing of the Mn2+ ions with Ce3+ ions in tetragonal sites (i.e. sites in which the Ce3+ ion is locally compensated by an F-interstitial in a (100) direction). At these centers efficient energy transfer from Ce3+ to Mn2+ takes place. However, a different behavior is noted when the specimens are irradiated. Measurements of X-ray- induced luminescence and thermoluminescence reveal that energy transfer does not appear to play an influential role in these latter processes. Instead of tetragonal sites, other Ce3+ centers, particularly cubic and trigonal photochromic centers, appear to dominate the X-ray-induced luminescence and the thermoluminescence.

Published
1986
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10. Energy transfer in CaF 2 :Ce, Mn.

Author

McKeever, S. W. S., Jassemnejad, B., Brown, M. D., Mathur, V. K., Abbundi, R. J., and Chan, H.

Abstract

Crystals of CaF2 containing different concentrations of Ce3+ and Mn2+ ions were investigated by means of optical absorption and photoluminescence. The results suggest the preferential pairing of the Mn2+ ions with Ce3+ ions in tetragonal sites (i.e. sites in which the Ce3+ ion is locally compensated by an F-interstitial in a (100) direction). At these centers efficient energy transfer from Ce3+ to Mn2+ takes place. However, a different behavior is noted when the specimens are irradiated. Measurements of X-ray- induced luminescence and thermoluminescence reveal that energy transfer does not appear to play an influential role in these latter processes. Instead of tetragonal sites, other Ce3+ centers, particularly cubic and trigonal photochromic centers, appear to dominate the X-ray-induced luminescence and the thermoluminescence. [ABSTRACT FROM PUBLISHER]

Published
1986
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16. Optimizing thermal conductivity in functionalized macromolecules using Langevin dynamics and the globalized and bounded Nelder-Mead algorithm.

Author

Ait Moussa A and Jassemnejad B

Abstract

Nanocomposites with high-aspect ratio fillers attract enormous attention because of the superior physical properties of the composite over the parent matrix. Nanocomposites with functionalized graphene as fillers did not produce the high thermal conductivity expected due to the high interfacial thermal resistance between the functional groups and graphene flakes. We report here a robust and efficient technique that identifies the configuration of the functionalities for improved thermal conductivity. The method combines linearization of the interatomic interactions, calculation, and optimization of the thermal conductivity using the globalized and bounded Nelder-Mead algorithm.

Published
2014
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17. Pump wavelength tuning of a near-infrared optical parametric oscillator.

Author

Jani MG, Powell RC, Jassemnejad B, and Stolzenberger R

Abstract

Optical parametric conversion in a potassium titanyl phosphate crystal with a tunable alexandrite laser was investigated as a function of pump wavelengths in the 700-800-nm region. Threshold energies and slope efficiencies for a doubly resonant oscillator configuration were measured for pump wavelengths of 744, 766, and 780 nm. Phase-matching conditions and a theoretical analysis using Sellmeier's equations provide good agreement with experimentally measured values of signal and idler wavelengths as a function of the pump wavelengths.

Published
1992
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