High-Frequency (95 GHz) EPR Spectroscopy To Characterize Spin Adducts
High-Frequency (95 GHz) EPR Spectroscopy To Characterize Spin Adducts
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用于表征自旋加合物的高频 (95 GHz) EPR 光谱
DOI：
10.1021/jp963066i
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发表时间：
1997
影响因子：
3.3
通讯作者：
E. Janzen
中科院分区：
文献类型：
--
作者：
T. Smirnova;A. Smirnov;R. Clarkson;R. Belford;Y. Kotake;E. Janzen
EPR自旋俘获实验通常在X波段（9.5GHz）进行，因为这种方法具有良好的浓度灵敏度和容易获得。自由基前体，其特征在于从各向同性的超精细耦合的分析和比较这些耦合因子与参考自旋加合物。这些实验遇到了两个主要的挑战：（i）来自许多碳中心自由基的自旋加合物具有几乎相同的g因子（导致在9.5 GHz处的光谱强烈重叠），以及（ii）可测量的超精细耦合对应于电子自旋与最近的原子核的相互作用。因此，很少或没有获得关于自旋加合物分子的整体结构的信息。其中一些困难可以通过在10倍高的频率95 GHz（W波段）下进行自旋捕获实验来克服。两个自旋加合物具有几乎相同的各向同性g因子（Δgiso = 1.2 × 10-4）的例子是苯溶液的ph...
EPR spin-trapping experiments are usually carried out at X-band (9.5 GHz) because of the good concentration sensitivity and ready availability of this method. The radical precursors are then characterized from an analysis of isotropic hyperfine coupling and comparison of these coupling factors with those for the reference spin adducts. These experiments encounter two major challenges: (i) spin adducts from many carbon-centered free radicals have g factors that are nearly the same (resulting in strongly overlapping spectra at 9.5 GHz), and (ii) measurable hyperfine couplings correspond to interactions of the electron spin with just the nearest nuclei. Therefore, very little or no information is obtained on the overall structure of the spin adduct molecule. Some of these difficulties can be overcome by carrying out spin-trapping experiments at 10-fold higher frequency, 95 GHz (W-band). Examples of two spin adducts with nearly the same isotropic g factors (Δgiso = 1.2 × 10-4) are the benzene solutions of ph...