EXCITATION TRAPPING IN LIQUID SOLUTIONS

Reversible transfer of photogenerated short-lived excitations to energ y accepters with relatively stable excited states was considered. When it occurs in the course of bimolecular encounters in Liquid solutions , it leads to energy conservation for a longer time. The conventional rate description of such a process even within the most sophisticated non-Markovian differential encounter theory is shown to be impossible due to divergency of the rate constants. The only alternative is the o riginal integral encounter theory. It provides a proper kinetic descri ption of delayed luminescence during encounter via energy donor as wel l as quantum yield of energy trapping by stable products (ions) escape d from encounters. The reasons are revealed why the usual reduction of integral kinetic theory to the differential one is inappropriate for either contact or remote reversible energy transfer between metastable states. The energy trapping via reversible ionization of the excited state is an extreme case that may be approached only within integral t heory by means of which the ion accumulation kinetics and charge separ ation quantum yield were obtained. (C) 1996 American Institute of Phys ics.