Vondrak Tomas, Meech Stephen R, Plane John M C
School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom.
J Chem Phys. 2009 Feb 7;130(5):054702. doi: 10.1063/1.3063658.
The photoelectron photoemission spectra and thresholds for low coverages of Li and K adsorbed on water-ice have been measured, compared with photoionization spectra of the gas-phase atoms, and modeled by quantum chemical calculations. For both alkali metals the threshold for photoemission is dramatically decreased and the cross section increased on adsorption to the water-ice surface. Quantum chemical calculations suggest that the initial state is formed by the metal atoms adsorbed into the water-ice surface, forming a state with a delocalized electron distribution. This state is metastable and decays on the hundreds of seconds time scale at 92 K. The decay is markedly faster for Li than for K, probably due to diffusion into the ice film.
已测量了吸附在水冰上的低覆盖度锂和钾的光电子发射光谱及阈值，并与气相原子的光电离光谱进行了比较，同时通过量子化学计算进行了建模。对于这两种碱金属，光发射阈值在吸附到水冰表面时显著降低，截面增大。量子化学计算表明，初始态是由吸附在水冰表面的金属原子形成的，形成了一种具有离域电子分布的状态。这种状态是亚稳态的，在92K下数百秒的时间尺度上会衰变。锂的衰变明显比钾快，这可能是由于扩散到冰膜中所致。
