IDENTIFICATION BY SURFACE-ENHANCED RAMAN-SPECTROSCOPY OF PHOTODEGRADATION PRODUCTS IN ORGANIC PHOTOCHROMES

In this paper we described a recently developed method, using surface enhanced Raman scattering (SERS) in silver colloids, to detect and ide ntify organic photochromes and their main photodegradation products. T he reported SERS data were obtained on the classical 6-nitro-8-methoxy -indolinospirobenzopyran. It was observed that SERS spectra of this ph otochrome arise mainly from open species (photomerocyanines), and disp lay vibrational features typical of the indolinic moiety. From specifi c SERS detection of totally degradated solutions, obtained under UV ir radiation, it pas possible to identify 5-nitrovanillin as the main pho todegradation product and to estimate the proportions of this species and that of the remaining photochrome in various solvents (acetonitril e and dioxane).