Laser Saturation Broadening in Flame Absorption and Fluorescence Experiments

Abstract

Atomic absorption and fluorescence excitation spectral profiles of Na in an air/C₂H₂ flame were scanned for high sample irradiances. The light source was a flash lamp pumped tuneable dye laser having a spectral bandwidth of less than 0.005 nm. The transmittance profile disappeared into the noise level of the unity transmittance line for an irradiance of 500 kW/cm². The halfwidth of the fluorescence excitation spectral profile increased from 0.0010 to 0.0019 nm for an increase in irradiance from 0.2 to 42 kW/cm². Exciting the 588.99 nm Na line with the laser tuned to 588.53 nm allowed baseline resolution to be achieved between the fluoresced light at 588.99 nm and the scattered light at 588.53 nm. The possibility of using such far wing excitation to improve detection limits for resonance fluorescence is discussed.