Systematic studies of rubidium-exposed surfaces by X-ray photoelectron spectroscopy and light-induced atom desorption

We systematically investigated various types of surfaces on which rubidium (Rb) atoms were deposited by X-ray photoelectron spectroscopy (XPS) and measured the light-induced atom desorption (LIAD) from those surfaces. The main surfaces of interest included synthetic quartz, yttrium metal, and paraffin. The Rb atoms deposited on quartz and yttrium surfaces by exposure to Rb vapor at room temperature were detected by XPS. Quartz is originally silicon dioxide. The yttrium surfaces were also oxidized, and Rb atoms reacted with oxygen on both surfaces. Conversely, Rb deposition was observed only at low temperatures on paraffin. Specifically, Rb atoms deposited on paraffin, which is not an oxygen compound, also formed oxygen compounds under ultrahigh vacuum conditions by reaction with the background gas. All examined surfaces showed a similar light wavelength or photon energy dependence, such that the LIAD rates increased with decreasing light wavelength. We presume that some types of compounds of alkali metal and oxygen can be ubiquitous sources for LIAD from many types of surfaces of alkali-metal vapor cells.