Abstract

Coulomb scattering in plasma results in strong broadening of the saturation resonances in ionic spectra. Collisions of two-level charged particles, studied theoretically¹ allows the interpretation of the Bennett hole broadening as the effect of diffusion in the velocity space. Calculations agree with the Lamb dip broadening observed in the frequency dependence of argon laser output power.² Several experiments have been performed recently on three-level laser spectroscopy of argon plasma.^3-6 In the three-level scheme, the resonances due to nonlinear interference (two-photon processes) might be observed in addition to saturation resonances (stepwise processes).

© 1992 Optical Society of America