The equilibrium configuration of liquid helium surrounding certain excited atomic states of helium and its effects on absorption and emission spectra

Abstract

The existence of microscopic bubbles in liquid helium surrounding localized electron states has been already established using an effective repulsive potential between the electron and helium atoms. We have found that the same effective potential can be used to calculate He-He interactions. The potential energy of such a system is viewed as the sum of (1) a Het molecular potential describing the interaction of the ground state atom with the "core ion" of the excited state, and (2) the effective electron-helium repulsion averaged over the excited electron orbital. The relative size of these two terms is shown to explain qualitatively the presence or absence of the characteristic "hump" in helium molecular potentials. The same techniques are extended to computing the perturbation of an excited helium atom by an arbitrary distribution of helium liquid atoms, assuming additivity of the interactions. Stable bubbles are then found to exist around certain atomic states, and the transition energies between excited states in liquid bubbles are shown to be in good agreement with the spectroscopic data of Dennis.