Photochromism of spirooxazines II. CARS‐investigation of solvent effects on the isomeric distribution

Abstract

Abstract The isomeric distribution of metastable “photomerocyanines” produced by UV‐photolysis of spiroindolinonaphthoxazine derivatives is examined by resonance‐enhanced CARS spectroscopy. — In unpolar and polar aprotic solvents CARS spectra prove the existence of two pairwise similar isomeric species. They differ, however, in Franck‐Condon factors for excitation S 0 → S 1 . In the protic solvent methanol an additional isomer is found for certain derivatives.