Year: 2024
Type: article
Abstract: The onset of retardation effects in atom-wall interactions is studied. It is shown that the transition range from the $1/{z}^{3}$ short-range (van der Waals) interaction to the $1/{z}^{4}$ long-range (Casimir) retarded interaction critically depends on the atomic properties and on the dielectric function of the material. For simple non-alkali-metal atoms (e.g., ground-state hydrogen and ground-state helium) interacting with typical dielectric materials such as intrinsic silicon, the transition to the retarded regime is shown to proceed at a distance of about 10 nm (200 Bohr radii). This is much shorter than typical characteristic absorption wavelengths of solids. Larger transition regimes are obtained for atoms with a large static polarizability such as metastable helium. We present a simple estimate for the critical distance, ${z}_{\mathrm{cr}}=137\phantom{\rule{0.16em}{0ex}}\sqrt{\ensuremath{\alpha}(0)/Z}$ atomic units, where $\ensuremath{\alpha}(0)$ is the static polarizability (expressed in atomic units) and $Z$ is the number of electrons of the atom.
Source: Physical Review A
Authors: T. Das, C. A. Ullrich, U. D. Jentschura
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4391843768