  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.
