Atomic fluorescence of sodium under continuous-wave laser excitation

Abstract

The tunable continuous‐wave (cw) dye laser has been shown to be capable of producing saturation conditions for sodium in an air‐acetylene flame. The experimental evidence indicates that the sodium doublet is a reasonably good approximation of a two‐level system. Saturation of the sodium 589.6‐nm line was observed at laser spectral irradiances of 10¹³ erg s⁻¹ cm⁻² nm⁻¹ and greater. Measurements of the absolute‐maximum fluorescence radiance under saturation conditions have been used to measure sodium concentration profiles in air‐hydrogen and air‐acetylene flames with spatial resolution on the order of 0.01 cm.