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.