COMPUTER-CONTROLLED SYSTEM DESIGNED TO MEASURE PHOTODEGRADATION OF PHOTOCHROMIC COMPOUNDS

In this paper, we describe a new, entirely computer-controlled apparat us designed for degradation studies of photochromic compounds. Photode gradation can be performed in three different ways using, in addition to the usual flash mode, the cyclic and continuous modes which more cl osely simulate daylight exposure conditions. In each mode, the ''fatig ue resistance'' parameter is computed. Moreover, the spectrokinetic pa rameters of photomerocyanine species can be obtained from the kinetic mode. Due particularly to the fully computer-controlled experimental s etup, the between-day reproducibility of the initial absorbance and fa tigue resistance determinations are better than 4% and 6%, respectivel y. Owing to the modular design of the menu-driven software, written in C language, the apparatus is very flexible and easy to use.