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Title:Electron spin-lattice relaxation in YB3+ - doped silicate glass
Author(s):Stevens, Sally Beth
Doctoral Committee Chair(s):Stapleton, H.J.
Department / Program:Physics
Discipline:Physics
Degree:Ph.D.
Genre:Dissertation
Subject(s):electron spin-lattice relaxation
YB3+-doped silicate glass
pulse saturation/recovery technique
Abstract:Relaxation rates of Yb3+ ions incorporated in low concentrations into a host silicate glass have been measured using a pulse saturation/recovery technique at 9.5 GHz over the temperature range 1.5-7.0 K. Compared with similar measurements made on crystalline material, the temperature dependence of the recovery rates for the two-phonon Raman process is anomalously weak (T6 instead of T9). This anomaly suggests the need to modify the Debye density of states. Fractal models have been suggested for the thermal properties of glasses and for similarly anomalous spin relaxation behavior in proteins. An alternate model is proposed here that is supported by other measurements of low temperature thermal transport properties in glasses. The relaxation rates are interpreted in terms of a "thermally effective" density of states consisting of only low frequency extended vibrational modes. This is smaller than the total density of vibrational modes (extended and localized) measured, for example, by neutron scattering. An estimate for the localization frequency or crossover frequency between these two regimes can be extracted from fits to the lowest concentration data.
Issue Date:1990
Genre:Dissertation / Thesis
Type:Text
Language:English
URI:http://hdl.handle.net/2142/25094
Rights Information:1990 Sally Beth Stevens
Date Available in IDEALS:2011-06-01
Identifier in Online Catalog:3480342


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