Title

Saturation Spectroscopy of an Optically Opaque Argon Plasma

Document Type

Article

Publication Date

2-2018

Abstract

A pure argon (Ar) plasma formed by a capacitively coupled radio-frequency discharge was analyzed using Doppler-free saturation spectroscopy. The expected line shape was a characteristic of sub-Doppler spectra in the presence of velocity-changing collisions, a narrow Lorentzian centered on a Doppler pedestal, but the observed line shapes contain a multi-peak structure, attributed to opacity of the medium. Laser absorption and inter-modulated fluorescence spectroscopy measurements were made to validate opacity as a driving factor of the observed line shapes. Spectral line shapes are further complicated by the spatial dependence of the pump laser, probe laser and of the absorbing medium, as well as the large absorbance of the transition under investigation. A numerical line shape was derived by accounting for the spatial variation of the pump and probe with a saturated line shape obtained from the rate equations for an equivalent two-level system. This simulated line shape shows good qualitative agreement with the trends observed in the data.

Comments

The "Link to Full Text" on this page loads the PDF of the chapter, furnished open-access through the Springer Nature SharedIt content-sharing initiative. Published by Springer as a work of the U.S. Federal government. Its text may be subject to foreign copyright protection.

DOI

10.1007/s00340-017-6869-6

Source Publication

Applied Physics B

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