Abstract

A new method is introduced for the measurement of photochemical or photobiological reaction rates. Based on linear response theory, the method uses a randomly modulated light source rather than a pulsed one, and uses cross-correlation analysis to extract the desired kinetic information. In operation, a randomly varying light source illuminates the reaction of interest, and the resulting fluctuations in reactant (or product) concentrations are monitored. Mathematical or instrumental cross correlation of the light source variations with those in component concentration then produces the familiar kinetic decay curve. Because the new method produces only minute concentration fluctuations, it can measure reaction rates near equilibrium; moreover, equilibrium position can be shifted by superimposing on the fluctuating light intensity a dc level. Also, because cross correlation is used, the method enjoys high signal-to-noise ratios. In the present study, the utility and practicability of the new technique are demonstrated through examination of the recombination kinetics of photolytically generated iodine atoms.

Tunable laser flash absorption: a new technique for measuring rates and yields of chemical reactions at high temperatures

William A. VonDrasek, Shigeo Okajima, John H. Kiefer, Paul J. Ogren, and Jan P. Hessler
Appl. Opt. 29(33) 4899-4906 (1990)

Rate of Volume Photolysis in Copper-Doped Silver Chloride*

T. R. Sliker
J. Opt. Soc. Am. 53(4) 454-457 (1963)

Tropospheric UV flux calculations and photolysis rates for use with zonally and diurnally averaged models

Gregory L. Matloff and Richard W. Stewart
Appl. Opt. 18(20) 3421-3425 (1979)

Simultaneous time-resolved measurement of the reaction rates and the refractive index of photopolymerization processes

Tomasz M. Bąk, J. Bianca Beusink, Vinod Subramaniam, and Johannes S. Kanger
Appl. Opt. 49(17) 3316-3322 (2010)

High-Resolution Kinetic Spectroscopy by a Multiple-Flash Method*

Henry H. Kramer, Maurice H. Hanes, and Edward J. Bair
J. Opt. Soc. Am. 51(7) 775-779 (1961)