Modeling of the Kinetics of Photoactivated Isotope Exchange O₂ ⇄ ZnO in a Flow-Through Reactor¹

Abstract—A three-channel model of interaction of the O₂ gas with zinc oxide during photoactivated oxygen isotope exchange (POIE) in a flow-through reactor is suggested including (1) photoadsorption, (2) exchange in the gas phase (homo-exchange), and (3) zinc oxide–gas exchange (hetero-exchange). In contrast to previous methods, the model includes photoadsorption as an increase in the rate of mixture renewal, which eliminates possible distortions of the time dependences of the calculated rates. Derivation of formulas and experimental data processing are given for POIE in the O₂–ZnO system used as an example, under illumination in interband and exciton absorption regions and in the region of absorption by defects in the structure of ZnO.