Excited-state atomic-beam studies of submonolayer adsorption on a fine mesh.
Excited-state atomic-beam studies of submonolayer adsorption on a fine mesh.
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细网格上亚单层吸附的激发态原子束研究。
DOI：
10.1103/physreva.38.3918
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Kocher
中科院分区：
文献类型：
--
作者：
Mccown;Taylor;Kocher
A surface dipole layer due to adsorbates on a fine mesh can produce localized electric fields capable of ionizing highly excited atoms. This effect is observed when an atomic beam containing high-Rydberg states of Li is incident on a degassed Au mesh having square openings 6 \ensuremath{\mu}m across. During the formation of an adlayer on the surface, the adsorbate field is analyzed through measurements of the excited-state atomic-beam flux transmitted through the mesh. The beam-transmission experiments confirm that the excited-state survival probability is surface-layer dependent. Two distinct dips are observed in the transmission as a function of time, during submonolayer adsorption of ${\mathrm{H}}_{2}$O and Li on the mesh surface. A cusp between the dips is interpreted as evidence for a change in the sign of the net surface dipole-moment density. These results are compatible with a Langmuir-type model for the survival probability of excited atoms subject to electric-field ionization as they pass through the mesh. Demonstrating that high-Rydberg atoms may be useful as probes for localized electric fields, the experiments serve as feasibility studies for a method of analysis which can readily determine surface dipole orientations and which may have the ability to detect changes in adsorbate coverage at the level of ${10}^{\mathrm{\ensuremath{-}}4}$--${10}^{\mathrm{\ensuremath{-}}5}$ monolayer.
A surface dipole layer due to adsorbates on a fine mesh can produce localized electric fields capable of ionizing highly excited atoms. This effect is observed when an atomic beam containing high-Rydberg states of Li is incident on a degassed Au mesh having square openings 6 \ensuremath{\mu}m across. During the formation of an adlayer on the surface, the adsorbate field is analyzed through measurements of the excited-state atomic-beam flux transmitted through the mesh. The beam-transmission experiments confirm that the excited-state survival probability is surface-layer dependent. Two distinct dips are observed in the transmission as a function of time, during submonolayer adsorption of ${\mathrm{H}}_{2}$O and Li on the mesh surface. A cusp between the dips is interpreted as evidence for a change in the sign of the net surface dipole-moment density. These results are compatible with a Langmuir-type model for the survival probability of excited atoms subject to electric-field ionization as they pass through the mesh. Demonstrating that high-Rydberg atoms may be useful as probes for localized electric fields, the experiments serve as feasibility studies for a method of analysis which can readily determine surface dipole orientations and which may have the ability to detect changes in adsorbate coverage at the level of ${10}^{\mathrm{\ensuremath{-}}4}$--${10}^{\mathrm{\ensuremath{-}}5}$ monolayer.