Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)
Unstable Intermediates in X-Irradiated Clathrate Hydrates: ESR and ENDOR of Tetramethylammonium Hydroxide Pentahydrate (TMNOH)
复制标题
X 射线辐照笼形水合物中的不稳定中间体：五水合氢氧化四甲铵 (TMNOH) 的 ESR 和 ENDOR
DOI：
10.1021/jp9524690
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
S. Schlick
中科院分区：
文献类型：
--
作者：
J. Bednarek;A. Lund;S. Schlick
在77 K下X射线照射五水合四甲基氢氧化铵（TMNOH）产生俘获电子、CH3·和（CH3）3N+CH2·自由基。捕获的电子被检测到漂白与可见光和漂白和未漂白的样品的光谱相减。甲基自由基的衰变开始于100 K，（CH3）3N+CH2·自由基的衰变开始于150 K.在130 K下测量的ESR谱具有最好的分辨率，并且是来自甲基自由基（13%）和（CH3）3N+CH2·自由基（87%）的贡献的叠加。谱线形状随温度变化的可逆性表明，在130 K下观察到的分辨率增加是由于涉及（CH3）3N+CH2·自由基的动力学效应。这些自由基的ESR谱可以通过假设两个α质子的超精细张量分量被两种类型的运动平均来模拟：CH2基团围绕C2v对称轴的旋转和该轴的进动或摆动。仿真中使用的参数。
X-irradiation of tetramethylammonium hydroxide pentahydrate (TMNOH) at 77 K produces trapped electrons, and CH3• and (CH3)3N+CH2• radicals. The trapped electrons were detected by bleaching with visible light and by subtraction of spectra from bleached and unbleached samples. The decay of the methyl radicals starts at ≈100 K and that of the (CH3)3N+CH2• radicals at ≈150 K. The ESR spectrum measured at 130 K has the best resolution and is a superposition of contributions from the methyl radicals (13%) and from the (CH3)3N+CH2• radical (87%). The reversibility of the line shapes with temperature variations suggested that the increased resolution observed at 130 K is due to dynamical effects involving the (CH3)3N+CH2• radicals. ESR spectra from these radicals can be simulated by assuming that the hyperfine tensor components for the two α protons are averaged by two types of motions: rotation of the CH2 group about the C2v symmetry axis and precession or wobbling of this axis. The parameters used in the simul...