SPACE-RESOLVED AND TIME-RESOLVED DIFFUSION-LIMITED BINARY REACTION-KINETICS IN CAPILLARIES - EXPERIMENTAL-OBSERVATION OF SEGREGATION, ANOMALOUS EXPONENTS, AND DEPLETION ZONE

An experimental investigation of one-dimensional, diffusion-limited A + B --> C chemical reactions is reported. The persistence of reactant segregation and the formation of a depletion zone is observed and expressed in terms of the universal time exponents: alpha (motion of the boundary zone), beta (width of instantaneous product formation zone), gamma (rate of instantaneous local formation of product), delta (rate of instantaneous global formation of product), etc. There is good agreement with the recently predicted and/or simulated values: alpha = 1/2, beta = 1/6, gamma = 2/3, delta = 1/2, in contrast to classical predictions (alpha = 0, beta = 1/2, gamma = 0, delta = -1/2). Furthermore, classically the segregation would not be preserved and there would be no formation of a depletion zone and no motion (just dissipation) of the reaction zone. We also discuss the relations to electrode oxidation-reduction reactions, i.e., A + C --> C where C is a catalyst, electrode, or "trap."