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

TL;DR

This paper investigates the physical mechanisms behind light-induced desorption of alkali atoms from glass surfaces in vapor cells, linking phenomena to surface science and identifying different processes based on photon energy and surface conditions.

Contribution

It provides a physical interpretation of light-induced desorption phenomena, connecting them to surface science concepts and distinguishing mechanisms based on photon energy and surface state.

Findings

Ultraviolet light causes desorption via neutralization of ionic adsorbates.

Visible light-induced desorption involves localized electronic excitation on metallic aggregates.

Understanding these mechanisms can improve alkali atom sources for atomic physics experiments.

Abstract

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.