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Master's Dissertation
DOI
10.11606/D.54.1979.tde-13102009-145733
Document
Author
Full name
Claudio Jose Magon
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1979
Supervisor
Title in Portuguese
Ressonância Paramagnética Eletrônica: teoria da medida. Relaxação eletrônica do hidrogênio atômico intersticial em CaF2 : evidência da difusão espectral.
Keywords in Portuguese
Difusão spectral
Hidrogênio em CaF2
Relaxação do spin eletrônico
Ressonância Paramagnética Eletrônica
RPE
Teoria da medida da RPE
Abstract in Portuguese
Na primeira parte deste trabalho, são discutidos alguns fatores que determinam a forma correta de operação de um espectro convencional de RPE. Um sistema específico, possuindo o circuito usual de "ponte de microonda", é analisado e as condições ideais para a realização da medida das duas componentes da susceptibilidade magnética complexa são determinadas. A seguir, mostra-mos os resultados encontrados para a relaxação eletrônica do hidrogênio atômico intersticial no CaF2. As medidas foram efetuadas utilizando técnicas de microonda pulsada, a 3 KGauss, para temperatura entre 1.6 e 4.2 0K. Os resultados experimentais foram interpretados, através dos dois processos seguintes: - difusão espectral entre spins pertencentes a uma mesma linha de absorção, e relaxação cruzada entre as diferentes componentes hiperfinas do espectro de absorção. A estes dois processos relacionamos tempos característicos da ordem de 10 ms a 60ms, respectivamente.
Title in English
Eletron Paramagnetic Resonance: theory of experiments. Electronic relaxation of the intersticial atomic hydrogen in CaF2: evidence of spectral diffusion
Keywords in English
Electron Paramagnetic Resonande
EPR
Hydrogen in CaF2
Relaxation of the electronic spin
Spectral Diffusion
Theory of experiments in EPR
Abstract in English
In the first part of this work some factors are discussed wich determine the correct way of operating of a convenctional EPR spectrometer. A specific system, having the usual "microwave bridge" circuit, is analysed and the complex conditions for the measurement of both components of the complex magnetic susceptibility are determined. We show results for the electronics relaxation of an interstitial atomic hydrogen in CaF2. Measurement were performed using the pulsed microwave technique at 3 kilogauss for temperatures between 1.6 and 4.2 0K.The experimental results were interpreted by means of two processes: - Spectral diffusion between spin states belonging to the same absorption line, and cross relaxation between different hyperfine components of the absorption spectrum. The characteristic times assigned to these processes are of the order or 10 ms and 60 ms respectively.
 
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ClaudioMagonM.pdf (8.37 Mbytes)
Publishing Date
2009-10-20
 
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