Monitoring and analyzing of a chemical reaction process using reaction heat-induced optical beam deflection

A reaction heat-induced optical beam deflection method has been applied for monitoring and analyzing a chemical reaction process. A reaction cell, whose bottom is a thin gold film, is immersed into a CC14 phase where a probe beam is passed. Reaction heat of the water phase is transferred to the gold film and the CCl4 phase, and thus a temperature gradient is generated in the CCl4 phase. This temperature gradient induces deflection of the probe beam. The deflection signal of a slow chemical reaction is considered as a convolution of the reaction rate and the instrumental response function, which is considered to be proportional to the decay curve of deflection signal for a very fast reaction or pulse reaction. The neutralization reaction between H2SO4 and NaOH, and the redox reaction between KMnO4 and Na2C2O4 are employed as a fast and slow model reaction, respectively. The deflection signals for the fast and slow reaction systems are monitored and compared. Furthermore, time profiles of the redox reaction rates are obtained by deconvolution treatments of the deflection signal data, and are compared with the results obtained by a transmittance method. The catalytic effect of Mn2+ in the KMnO4−Na2C2O4 redox reaction is examined as well. Improvements of this method are also discussed.