We consider the time dependence of the absorption coefficient due to the photoinduced chemical reaction (PCR) and species diffusion to calculate the temperature rise in the thermal-lens (TL) effect. The TL signal at the detector plane is also calculated. This theoretical approach removes the restriction that the PCR time constant is much greater than the characteristic TL time constant, which was assumed in a previously published model. Hydrocarbon fuel and aqueous Cr(VI) samples are investigated, and quantitative experimental results for the thermal, optical, and PCR properties are obtained. While similar results were obtained for the Cr(VI) solution using the previous and present models, the relative difference between the PCR time constants extracted from the same experimental data for a hydrocarbon fuel sample is found to be more than 220%. This demonstrates the significant difference of the two models.
© 2009 Optical Society of America
Original Manuscript: September 3, 2009
Revised Manuscript: September 21, 2009
Manuscript Accepted: September 22, 2009
Published: November 4, 2009
Nelson G. C. Astrath, Francine B. G. Astrath, Jun Shen, Jianqin Zhou, Kirk H. Michaelian, Craig Fairbridge, Luis C. Malacarne, Paulo R. B. Pedreira, A. N. Medina, and Mauro L. Baesso, "Thermal-lens study of photochemical reaction kinetics," Opt. Lett. 34, 3460-3462 (2009)