The influence of the stationary electric field upon the resonance absorption of microwaves in HeII

TL;DR

This study explores how a stationary electric field affects microwave resonance absorption in superfluid helium, revealing a linear Stark effect and providing insights into helium's polarizability and dipole moment.

Contribution

It demonstrates the splitting of resonance lines in superfluid helium under electric fields and estimates helium's polarizability and dipole moment, advancing understanding of helium's electromagnetic properties.

Findings

Resonance absorption line splits into two symmetric lines under electric field.

Splitting magnitude increases linearly with electric field strength.

Spectral line profile includes a narrow resonance and a broad background.

Abstract

The interaction between electromagnetic microwaves (40-200 GHz) and superfluid helium in a stationary electric field has been investigated experimentally. It is found that the narrow line of resonance absorption at the roton frequency is split in the electric field into two symmetric lines. The splitting magnitude increases almost linearly with the electric field, which suggests a linear Stark effect. The results obtained point of orientational polarizability and dipole moment (10^(-34)C*m) in HeII. It is shown that the spectral line profile consists of two parts - a narrow line of resonance absorption (or induced radiation when superfluid stream are generated) and a broad background. The background with agrees well with the latest neutron data for the roton line.