Spin-Orbit Coupling in Molecular Complexes beyond van der Waals Regime:Key Factors for Further Splitting of 2P3/2 Ground State
We report a joint spectroscopic and theoretical study probing spin-orbit coupling(SOC)in a variety of molecular complexes between an io-dine atom and a ligand(L)with L ranging from Ar,HF to formic/acetic acids,and glycine/N-methylated glycine derivatives.Cryogenic photoelectron spectroscopy of L·I-(L=HCOOH,CH3COOH)reveals three dis-tinct peaks,identified as three SOC states,denoted as X(1/2),A(3/2),and B(1/2)for the cor-responding neutrals.The X and A separation △EXA is measured to be 0.10 eV for both,whereas the X and B gap △EXB is 0.98 and 0.97 eV for formic and acetic acid,respectively.These new △EXA values are compared with the previously reported values for the molecular complexes L·I·with L=Ar,HF,glycine,and N-methylated glycines.All together these com-plexes encompass a diversity of intermolecular interactions,from van der Waals to weak and strong hydrogen bonding.While the △EXB remains similar,the △EXA is shown to be extreme-ly sensitive to the type of ligands and interactions,spanning from 5 meV to 150 meV.High-level relativistic quantum calculations including explicit SOC formulism nicely reproduce all experimental SOC splitting.A direct correlation between the magnitude of △EXA with the in-termolecular interaction strength or bond distance of the neutral complexes—the stronger in-teraction(shorter bond length),the greater splitting,is established.
Spin-orbit couplingNegative ion photoelectron spectroscopyHydrogen bond-ed clusters
曹文锦、王学斌
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美国西北太平洋国家实验室物理科学系,里奇兰99352
自旋轨道耦合 光电子能谱 氢键配位化合物
U.S.Department of Energy(DOE),Office of Science,Office of Basic Energy Sciences,Division of Chemical Science,Geosciences,and Bio