Misochko Eugenii Ya, Akimov Alexander V, Goldschleger Ilya U, Tyurin Danil A, Laikov Dimitri N
Institute of Problems of Chemical Physics of the Russian Academy of Sciences, 142432 Chernogolovka, Moscow Region, Russia.
J Chem Phys. 2005 Jan 15;122(3):34503. doi: 10.1063/1.1829058.
Xenon fluoride radicals were generated by solid-state chemical reactions of mobile fluorine atoms with xenon atoms trapped in Ar matrix. Highly resolved electron spin resonance spectra of XeF* were obtained in the temperature range of 5-25 K and the anisotropic hyperfine parameters were determined for magnetic nuclei 19F, 129Xe, and 131Xe using naturally occurring and isotopically enriched xenon. Signs of parallel and perpendicular hyperfine components were established from analysis of temperature changes in the spectra and from numerical solutions of the spin Hamiltonian for two nonequivalent magnetic nuclei. Thus, the complete set of components of hyperfine- and g-factor tensors of XeF* were obtained: 19F (Aiso=435, Adip=1249 MHz) and 129Xe (Aiso=-1340, Adip=-485 MHz); g(parallel)=1.9822 and g(perpendicular)=2.0570. Comparison of the measured hyperfine parameters with those predicted by density-functional theory (DFT) calculations indicates, that relativistic DFT gives true electron spin distribution in the 2Sigma+ ground-state, whereas nonrelativistic theory underestimates dramatically the electron-nuclear contact Fermi interaction (Aiso) on the Xe atom. Analysis of the obtained magnetic-dipole interaction constants (Adip) shows that fluorine 2p and xenon 5p atomic orbitals make a major contribution to the spin density distribution in XeF*. Both relativistic and nonrelativistic calculations give close magnetic-dipole interaction constants, which are in agreement with the measured values. The other relativistic feature is considerable anisotropy of g-tensor, which results from spin-orbit interaction. The orbital contribution appears due to mixing of the ionic 2Pi states with the 2Sigma+ ground state, and the spin-orbit interaction plays a significant role in the chemical bonding of XeF*.
通过移动氟原子与捕获在氩基质中的氙原子的固态化学反应生成了氟化氙自由基。在5 - 25 K的温度范围内获得了XeF的高分辨率电子自旋共振光谱，并使用天然存在的和同位素富集的氙确定了磁核19F、129Xe和131Xe的各向异性超精细参数。通过对光谱温度变化的分析以及对两个不等价磁核的自旋哈密顿量的数值解，确定了平行和垂直超精细分量的符号。因此，获得了XeF的超精细张量和g因子张量的完整分量集：19F（Aiso = 435，Adip = 1249 MHz）和129Xe（Aiso = - 1340，Adip = - 485 MHz）；g（平行）= 1.9822，g（垂直）= 2.0570。将测量的超精细参数与密度泛函理论（DFT）计算预测的参数进行比较表明，相对论DFT给出了2Σ+基态中真实的电子自旋分布，而非相对论理论则极大地低估了氙原子上的电子 - 核接触费米相互作用（Aiso）。对获得的磁偶极相互作用常数（Adip）的分析表明，氟2p和氙5p原子轨道对XeF中的自旋密度分布起主要作用。相对论和非相对论计算都给出了接近的磁偶极相互作用常数，这与测量值一致。另一个相对论特征是g张量的相当大的各向异性，这是由自旋 - 轨道相互作用引起的。轨道贡献是由于离子2Π态与2Σ+基态的混合而出现的，并且自旋 - 轨道相互作用在XeF的化学键合中起重要作用。
