Orientation dependence of electron spin phase memory relaxation times in copper(II) and vanadyl complexes in frozen solution
Orientation dependence of electron spin phase memory relaxation times in copper(II) and vanadyl complexes in frozen solution
复制标题
冷冻溶液中铜(II)和氧钒络合物电子自旋相记忆弛豫时间的方向依赖性
DOI：
10.1002/ijch.199200041
复制
发表时间：
1992
影响因子：
3.2
通讯作者：
G. Eaton
中科院分区：
文献类型：
--
作者：
Jingjie Du;K. More;S. Eaton;G. Eaton
在 22、50 和 100 K 下测量了氧钒基 5-(4-羧基苯基)-10, 15, 20-三甲苯基卟啉，在 50 和 100 K 下测量了双(二乙基二硫代氨基甲酸铜)(II)，以及在 5, 10, 15,冷冻溶液中 50、70 和 100 K 下的 20-四甲苯基卟啉。 Tm 通过将单指数拟合到两脉冲电子自旋回波数据来确定。 Tm 值很大程度上取决于磁场中分子的方向。当磁场沿着主轴或沿着频谱中的非规范转折点时，可以获得更长的值。在中间方向观察到较短的 Tm 值。 Tm 的取向依赖性归因于分子运动。所检查的三个系统的 EPR 谱近似为轴向，因此相关运动是分子 z 轴相对于外部磁场的运动。当共振条件对分子 z 轴方向的变化不太敏感时， Tm 值较长（弛豫较慢）。更短的 Tm 值（更快的弛豫）发生在共振条件对分子 z 轴方向的变化更敏感的方向上。
The orientation dependence of the electron spin phase memory relaxation time (T) was measured for vanadyl 5-(4-carboxyphenyl)-10, 15, 20-tritolylporphyrin at 22, 50, and 100 K, copper(II) bis(diethyldithiocarbamate) at 50 and 100 K, and copper(II) 5, 10, 15, 20-tetratolylporphyrin at 50, 70, and 100 K in frozen solution. Tm was determined by fitting a single exponential to two-pulse electron spin echo data. The values of Tm were strongly dependent on the orientation of the molecule in the magnetic field. Longer values were obtained when the magnetic field was along a principal axis or along a non-canonical turning point in the spectrum. Shorter values of Tm were observed at intermediate orientations. The orientation dependence of Tm is attributed to molecular motion. The EPR spectra for the three systems examined are approximately axial, so the relevant motion is motion of the molecular z axis with respect to the external magnetic field. Longer values of Tm (slower relaxation) occur for orientations at which the resonant condition is less sensitive to a change in orientation of the molecular z axis. Shorter values of Tm (faster relaxation) occur at orientations for which the resonant condition is more sensitive to a change in orientation of the molecular z axis.