Abstract

Intracavity dye laser absorption spectroscopy (IDLAS) has been used in the past to detect weakly absorbing species. However, for the method to be applicable to areas such as chemical kinetics, where the concentration of a reactive species must be monitored, the absorpiton must be quantified. IDLAS has been used to detect nitrogen dioxide in the visible spectral region via absorption in the vibronic bands of the ${\tilde{A}}^2{B}_2\leftarrow {\tilde{X}}^2{A}_1$ system. Experimentally a sample cell is placed within the extended cavity of a cw dye laser pumped by an argon-ion laser. The dye laser waveform is scanned with a narrow bandwidth monochromator; the signal is detected photoelectrically and processed by an electrometer/strip chart recorder combination. To determine the extent of absorption, spectra are recorded with and without absorber in the sample cell for a number of absorber concentrations and at a given absorption frequency the dye laser intensities—I and I₀, respectively—aremeasured. The results indicate that over a limited range there is a linear dependence of the apparent absorbance, log(I₀/I), on the absorber concentration. System sensitivity is compared for operation of the dye laser both near and far above lasing threshold.

© 1985 Optical Society of America