Simulation methods for looping transitions

被引:16
作者
Gaffney, BJ
Silverstone, HJ
机构
[1] Florida State Univ, Natl High Magnet Field Lab, Tallahassee, FL 32310 USA
[2] Florida State Univ, Inst Mol Biophys, Tallahassee, FL 32310 USA
[3] Johns Hopkins Univ, Dept Chem, Baltimore, MD 21218 USA
关键词
simulation of S > 1; looping transition; chromium ion; iron ion; transferrin;
D O I
10.1006/jmre.1998.1526
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
Looping transitions occur in field-swept electron magnetic resonance spectra near avoided crossings and involve a single pair of energy levels that are in resonance at two magnetic field strengths, before and after the avoided crossing. When the distance between the two resonances approaches a linewidth, the usual simulation of the spectra, which results from a linear approximation of the dependence of the transition frequency on magnetic field, breaks down. A cubic approximation to the transition frequency, which can be obtained from the two resonance fields and the field-derivatives of the transition frequencies, along with linear (or better) interpolation of the transition-probability factor, restores accurate simulation. The difference is crucial for accurate line shapes at fixed angles, as in an oriented single crystal, but the difference turns out to be a smaller change in relative intensity for a powder spectrum. Spin-3/2 Cr3+ in ruby and spin-5/2 Fe3+ in transferrin oxalate are treated as examples, (C) 1998 Academic Press.
引用
收藏
页码:57 / 66
页数:10
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