Determination of quantum yields and product spectra by studying reversible photoisomerizations in solution

A procedure is presented which combines the method of Fischer (J. Phys. Chem. 71 (1967) 3704-3706) with techniques for calculating the absorbance in the photostationary state, in particular the method of formal integration and that of ''transformed time''. The proposed procedure thus enables the quantum yields of a reversible photoisomerization as well as the absorption spectrum of the photoproduct to be calculated from a set of reaction spectra A(t,lambda) measured at sufficiently low exposure times t. Finally, using the method presented here, the photoisomerizations of several model compounds were analysed to demonstrate its applicability and performance. (C) 1997 Elsevier Science S.A.