Laser spectroscopy on the Stark effect of the level of He I

In electric fields , shift and splitting of the line of He I were measured spectroscopically by crossing a beam of metastable He atoms with a frequency-doubled cw Ti:sapphire laser beam. We deduced the difference of the scalar polarizabilities, the tensor polarizability and the energy separation of closest approach of the Stark sublevels with m = 0 and negative reflection parity at . The polarizabilities agree with calculated values. By comparing the measured energy separation with theory, we deduced that the scalar polarizabilities of the and differ slightly by .