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Master's Dissertation
DOI
10.11606/D.54.1992.tde-28042014-113640
Document
Author
Full name
Sergio da Costa Saab
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1992
Supervisor
Committee
Terrile, Maria Cristina (President)
Martin Neto, Ladislau
Walmsley, Lygia Christina de Moura
Title in Portuguese
Estudo por R.P.E. do cobre (II) (α - amino isobutirato)
Keywords in Portuguese
Aminoácido
Fator g
Largura de linha
Abstract in Portuguese
Neste trabalho são apresentados estudos de Cu(α-AIB)2 utilizando-se a técnica de RPE à temperatura ambiente nas freqüências de 9,7 GHz e 34 GHz. Os espectros de R. P. E. mostram uma única ressonância tanto em banda X (9,7 GHz) quanto em banda Q (34 GHz), devido ao efeito de estreitamento por troca. Os valores das componentes do tensor g e da largura de linha foram determinados a partir dos espectros obtidos variando o ângulo entre H e os eixos do cristal a´, b e c em três planos a´b, a´c, e bc. O tensor g reflete as propriedades moleculares do complexo, com o íon Cu(II) em uma simetria axial e também a orientação destas moléculas dentro da cela unitária do cristal. A variação angular da largura de linha é analisada em termos da simetria do íon Cu(II) na rede cristalina e das contribuições das interações dipolar e Zeeman Residual. O parâmetro da interação de troca |J'|, é obtido através da contribuição da interação Zeeman residual na largura de linha, |J'| ~ 0,34K. É também observada uma característica magnética bidimensional no complexo Cu(α-AIB)2 concordando com os resultados cristalográficos.
Title in English
Study by EPR copper (II) (α - amino isobutyrate)
Keywords in English
Amino acid
G factor
Linewidth
Abstract in English
In this work is presented a study of the complex Cu(α-AIB) 2 using EPR spectroscopy at room temperature, in two frequency bands (9.7 and 34 GHz). The EPR spectra, in both bands and any direction of the extremal magnetic field consist of a single resonance line. This fact can be understood considering the exchange narrowing between non-equivalent Cu(II) íons. The elements of the g tensor and line width were determined from the angular dependence of the EPR spectrum, in three ortogonal crystal planes a´b, a´c and ab (a´=b x c). The angular dependence of the g tensor reflects the molecular properties of the complex Cu(α-AIB)2 the axial symmetry of the molecule and the orientation on the crystal unit cell. The most important contributions to the line width were found to be: 2D dipolar interactions, the residual Zeeman effect and defects compatible to the symmetry of the crystal. The Exchange parameter, |J'| ~ 0.34K, was obtained from the residual Zeeman contribution to the line width (Q band). The low dimension found for dipolar interations agrees with crystallographic results.
 
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Publishing Date
2014-04-30
 
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