Three-Pulse ELDOR Theory Revisited
Three-Pulse ELDOR Theory Revisited
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DOI：
10.1007/s00723-014-0541-7
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发表时间：
2014-06-01
影响因子：
1
通讯作者：
Zaripov, R. B.
中科院分区：
文献类型：
--
作者：
Salikhov, K. M.;Khairuzhdinov, I. T.;Zaripov, R. B.
当前的三脉冲电子双共振（PELDOR）理论已推广到成对或成组的顺磁粒子（自旋标记）具有基本上重叠或重合的电子顺磁共振（EPR）谱的情况。全面分析了无序系统中成对的顺磁自旋 A1/2 粒子之间的偶极-偶极相互作用引起的 PELDOR 信号调制。已经表明，当成对的自旋标记的 EPR 谱不重叠时，PELDOR 信号包含与当前理论中考虑的情况相反的附加项。在无序系统中，自旋标记对具有特征偶极相互作用频率。根据当前的自旋标记对理论，PELDOR 信号揭示了具有该特征频率的调制。在这项工作中获得的附加项不会改变自旋标签对的 PELDOR 信号的调制频率。然而，在分析 PELDOR 信号的幅度和 PELDOR 信号的调制幅度时，应考虑这些附加项。已经根据自旋标签对的结果概述了处理包含三个或更多自旋标签的组的 PELDOR 数据的一致方法。还分析了自旋翻转和分子运动或分子异构化如何影响 PELDOR 实验中自旋标记之间相互作用的表现。已经进行了稳定双自由基（含有 1-氧基-2,2,5,5-四甲基吡咯啉-3-基自旋标签的双自由基 I 和含有 3-咪唑啉自旋标签的双自由基 II）的 PELDOR 实验。结果已在本工作中开发的理论内得到解释。
The current theory of three-pulse electron double resonance (PELDOR) has been generalized to the case, when paramagnetic particles (spin labels) in pairs or groups have the electron paramagnetic resonance (EPR) spectra, which overlap essentially or coincide. The PELDOR signal modulation induced by the dipole-dipole interaction between paramagnetic spin A1/2 particles in pairs embedded in disordered systems has been analyzed comprehensively. It has been shown that the PELDOR signal contains additional terms in contrast to the situation considered in the current theory, when the EPR spectra of the spin labels in the pairs do not overlap. In disordered systems, the pairs of spin labels have the characteristic dipolar interaction frequency. According to the current theory for pairs of spin labels, the PELDOR signal reveals the modulation with this characteristic frequency. The additional terms, which are obtained in this work, do not change the modulation frequency of the PELDOR signal for pairs of spin labels. However, these additional terms should be taken into account when analyzing the amplitude of the PELDOR signal and the amplitude of the modulation of the PELDOR signal. The consistent approach to treating the PELDOR data for the groups containing three or more spin labels has been outlined on the basis of the results for pairs of spin labels. It has been also analyzed how the spin flips and molecular motion or molecular isomerization can affect the manifestation of the interaction between the spin labels in PELDOR experiments. PELDOR experiments for the stable biradicals (biradicals I containing 1-oxyl-2,2,5,5-tetramethylpyrroline-3-yl spin labels and biradicals II containing 3-imidazoline spin labels) have been performed. The results have been interpreted within the theory developed in this work.