Lifetime of the Triplet State of Methylene Blue in the Presence of Salicylic Acid

A break the lifetime of MBH2+ (T1) vs. salicylic acid concentration plot occurs at around 6 × 10 E(-5) M (corresponding to pH of the solution 4.3). This pH is close to pK1 of leucomethylene blue. The quantum yields of 2,3-dihydroxybenzoic acid increase with increasing salicylic acid concentration over the whole range investigated (9 × 10 E(-6) - 3 × 10 E(-4)M); the growth of the quantum yields becomes more pronounced for pH < 4.35, too.