**Modeling the Dynamics of Secondary Photoreactions***Russian Journal of Physical Chemistry A* (IF0.691), Pub Date : 2021-08-22*, DOI: **10.1134/s0036024421080203*Morozov, V. A.### Abstract

A system of equations is obtained for describing the dynamics of the secondary photoreaction of two-level molecules emitting spontaneous fluorescence at initial excitation of one of them. The system is derived using the Schrödinger equation for the compound system of a reagent molecule, a reaction product molecule, and a quantized radiation field. Unlike those commonly used in similar modeling, optical Bloch equations describing the dynamics of a non-selective (collective) population of the ground states of two molecules (i.e., the total number of molecules of a pair in their ground states), the system of equations (and its generalization allowing for the longitudinal and transverse relaxation of excited states of molecules) allows estimates of the relative number of reagent molecules and the product in their ground states, the use of which provides a complete idea of the effectiveness of the reaction.