Nuclear resonant scattering of synchrotron radiation by physisorbed Kr on TiO2_{2}(110) surfaces in multilayer and monolayer regimes

Physisorbed Kr layers on TiO$_{2}$(110) surfaces were investigated by means of nuclear resonant scattering (NRS) of synchrotron radiation at Kr thicknesses ranging from multilayer to monolayer. The NRS intensity was measured as a function of the Kr exposure, from which the NRS signal corresponding to monolayer was estimated as 0.23 cps. The time spectra measured at various thicknesses showed a monotonous decay without any quantum beat features. The recoiless fraction $f$ evaluated from the analysis of the time spectrum revealed a substantial reduction upon temperature rise from 19 to 25 K. As its origin, an order-disorder phase transition of the monolayer Kr is proposed.Comment: 7 pages, 6 figure

Resonant tunneling of Hydrogen in Pd

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Nuclear resonant scattering of synchrotron radiation by physisorbed Kr on TiO2(110) surfaces in multilayer and monolayer regimes

Physisorbed Kr layers on TiO2(110) surfaces were investigated by means of nuclear resonant scattering (NRS) of synchrotron radiation at Kr thicknesses ranging from multilayer to monolayer. The NRS intensity was measured as a function of the Kr exposure, from which the NRS signal corresponding to monolayer was estimated as 0.23 cps. The time spectra measured at various thicknesses showed a monotonous decay without any quantum beat features. The recoilless fraction f evaluated from the analysis of the time spectrum revealed a substantial reduction upon temperature rise from 19 to 25 K. As its origin, an order-disorder phase transition of the monolayer Kr is proposed

Classification of Light-Induced Desorption of Alkali Atoms in Glass Cells Used in Atomic Physics Experiments

We attempt to provide physical interpretations of light-induced desorption phenomena that have recently been observed for alkali atoms on glass surfaces of alkali vapor cells used in atomic physics experiments. We find that the observed desorption phenomena are closely related to recent studies in surface science, and can probably be understood in the context of these results. If classified in terms of the photon-energy dependence, the coverage and the bonding state of the alkali adsorbates, the phenomena fall into two categories: It appears very likely that the neutralization of isolated ionic adsorbates by photo-excited electron transfer from the substrate is the origin of the desorption induced by ultraviolet light in ultrahigh vacuum cells. The desorption observed in low temperature cells, on the other hand, which is resonantly dependent on photon energy in the visible light range, is quite similar to light-induced desorption stimulated by localized electronic excitation on metallic aggregates. More detailed studies of light-induced desorption events from surfaces well characterized with respect to alkali coverage-dependent ionicity and aggregate morphology appear highly desirable for the development of more efficient alkali atom sources suitable to improve a variety of atomic physics experiments.Comment: 6 pages, 1 figure; minor corrections made, published in e-Journal of Surface Science and Nanotechnology at http://www.jstage.jst.go.jp/article/ejssnt/4/0/4_63/_articl

On the reflection symmetries of atoms and diatomic molecules: derivation of

The reflection symmetries of atoms and diatomic molecules are discussed in detail. We introduce the classification of the atomic states in light of their transformational properties for reflection, and show the absence of the negative terms, namely S− terms, in the one- and two-electron systems. The selection rule that no dipole transition occurs between S terms is readily derived using only the reflection symmetry. We also give an elementary proof of the rule on determining molecular Σ± terms from atomic terms. Furthermore, based on the picture of the electron configuration in molecular orbitals, general functional forms of Σ± states are shown. By using these forms, we derive the resultant Σ± terms for the electron configurations that have not been treated previously, and make clear what causes the correlation between the reflection symmetry and spin multiplicity. The way shown in the present paper enables determination of Σ± terms arising from any electron configuration