High resolution optogalvanic spectroscopy of He 3 1,3D–2 3P transitions

Abstract

He 3 1,3D–2 3P lines have been investigated by optogalvanic spectroscopy in the hollow cathode discharge of He to reveal the presence of the 3 1D2–2 3P2 component which is predicted at 0.0764 cm−1 above the 3 1D2–2 3P1 line appearing at 17 018.137±0.004 cm−1. The assignment of the latter has also been experimentally established by the present study through the use of optogalvanic double resonance methods. The spin-orbit interaction of the 3 1D2 level with the 3 3D2 level is responsible for the appearance of the 3 1D2–2 3P2 line. The relaxation processes among the 3 1D, 3 3D, and 2 3P levels have also been briefly discussed on the basis of the observations of mysterious dips on the double resonance signals and of a broad background signal on Doppler-free intermodulation spectrum.