Noble-gas atoms characterized by hyperfine frequency shift of lithium atom

Abstract

We report an experimental and theoretical study on the shift of the hyperfine splitting frequency of ground-state Li atoms in noble gases, He, Ne, Ar, and Xe. The frequency shift is due to the change in the electron-spin density at the Li nuclei induced by collisions to the noble-gas atoms. The electron density is calculated along the interatomic distance in a pseudopotential and a dispersion potential. Based on the measured and the calculated frequency shifts, we find the importance of attractive force in collisions to helium as well as heavy noble-gas atoms. Taking advantage of the simple energy structure of the Li atom, we obtain the s wave scattering length for free electrons on noble-gas atoms by using the hyperfine splitting frequency as a precise measure.

Isotope study of the nonlinear pressure shifts of $^{85}$Rb and $^{87}$Rb hyperfine resonances in Ar, Kr, and Xe buffer gases

“…It is the dominant spin interaction responsible for the linear pressure shift. [7][8][9] The potential δ A(R) is generally expected to change sign at least once at small R for our molecules of interest. 8,9,35,37,[51][52][53][54][55][56][57][58] As a result, the sign of the fitting parameters for binary and molecular shifts need not agree.…”

“…[3][4][5][6] In these devices, collisions with the gas shift the resonant frequencies ν away from their free-atom values ν 0 by an amount, ν − ν 0 , that depends on the gas composition, pressure, and temperature. Known as the "pressure" shift, [7][8][9][10] these shifts are very nearly linear with the buffer-gas pressure p at typical partial-vacuum cell pressures. Fig.…”