Abstract
Principal component analysis (PCA) of a series of absorption and emission spectra of 2-(2'-hydroxyphenyl)benzimidazole (HBI) in aqueous solutions in the pH range from 1.11 to 12.3 and 3.85 to 9.62, respectively, reveals the presence of three contributing components both in the ground and in the excited state. The combination of PCA with global analysis (PCGA) confirms the previously proposed reaction mechanism and allows the determination of pKa values, pure component spectra, and concentration profiles of the ground- and excited-state species in spite of their strong spectral overlap. PCGA is proved to be a powerful complement to standard nonlinear least-squares analysis of physicochemical systems.
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