Zero-field level crossing of the 633 nm Ne line in resonance absorption

Abstract

The authors have investigated the zero-field level crossing lineshape in resonance absorption. A single-mode HeNe laser beam at 633 nm is applied to an external neon-gas absorption cell in a longitudinal magnetic field. They compare the measured lineshapes with theoretical predictions. Two superposed nonlinear Lorentzian-shaped resonances, known as the population effect of the 2p4-3s2 transition and the Zeeman coherence effect of the lower 2p4 level, appear on the background caused by the inhomogeneous broadening. Taking into account the background and the power broadening the authors obtain the linewidths at zero pressure gamma (2p4,3s2)=(7.7+or-2.1) MHz and gamma (2p4)=(8.4+or-1.2) MHz. For the neon pressure broadening the authors get for pressures below 200 Pa (1.5 Torr) d gamma (2p4,3s2)/dp=0.20+or-0.02 MHz Pa-1 and d(2p4)/dp=0.040+or-0.007 MHz Pa-1. Their values are in acceptable agreement with the values obtained with other spectroscopic methods.