The concentration dependence of the normalized photostability of 1,3,5,7,8-pentamethyl-2,6-di-t-butylpyrromethene-difluoroborate complex (PM-597) methanol solutions

The concentration invariance of normalized photostability,the accumulated energy needed for a 50% reduction in dye concentration in units of GJ mole−1, is investigated for 1,3,5,7,8-pentamethyl-2,6-di-t-butylpyrromethene-difluoroborate complex (PM-597) methanol solutions. Normalized photostability is purported to be concentration invariant. Result from this investigation, however, demonstrated increasing normalized photostabilities for decreasing concentrations, rendering normalized photostability inapplicable to PM-597 photodegradation.