Electron exchanges in nuclear spin conversion of hydrogen physisorbed on diamagnetic insulators
Electron exchanges in nuclear spin conversion of hydrogen physisorbed on diamagnetic insulators
复制标题
物理吸附在反磁性绝缘体上的氢的核自旋转换中的电子交换
DOI：
10.1140/epjb/e2014-50282-2
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
F. Ghiglieno
中科院分区：
文献类型：
--
作者：
E. Ilisca;F. Ghiglieno
模型提供和讨论，以解释新的实验上的氢“物理吸附”的电介质和抗磁性表面的邻-对位转换。静电和动态分子表面相互作用补充超精细接触一般比磁性的更有效。库仑排斥引起分子和表面电子的交换，并激发三重态自旋，这是有效的角动量转移到催化剂。转换时间是两种能量之比的平方：交换能量和激发能量。发现的主要通道组成的三重激发的顺序的电子伏特，诱导分子表面交换约一百毫电子伏。它解释了在MOF样本上观察到的约一分钟的锌和氧速率以及在ASW上观察到的约十倍慢的速率。同样的机制也出现在瞬态政权，但更快。最后，它还解释了几个小时的转换观察到的间隙氢在硅的过渡到导带引起的约10毫电子伏的电子交换。显示了MOF和ASW构型的分子表面轨道几何形状，展开时的量子路径表现出连续的对称性破缺。
Models are provided and discussed to interpret new experiments on the ortho-para conversion of hydrogen “physisorbed” on dielectric and diamagnetic surfaces. Electro-static and dynamical molecule-surface interactions complemented by hyperfine contacts are shown to be generally more effective than the magnetic ones. Coulomb repulsion induces exchanges of molecular and surface electrons and excites triplet spin states which are effective in the angular momenta transfers to the catalyst. The conversion time is obtained as the square of a ratio of two energies: the exchange and excitation ones. The main channel is found composed of triplet excitations of the order of the eV, induced by molecule-surface exchanges of about a hundred of meV. It explains the zinc and oxygen rates of about one minute observed on the MOF samples as well as the about ten times slower ones on the ASW. The same mechanism is also shown to occur in the transient regime, but faster. Finally it explains also the conversion of a few hours observed for interstitial hydrogen in silicium by transitions to the conduction band induced by about 10 meV electron exchanges. The molecule-surface orbital geometries of the MOF and ASW configurations are displayed and the quantum path when unfolded exhibits the successive broken symmetries.