“…The results described above indicate that the fast photo-voltage transients reported here are associated with pK3, which in dioxane/water is 5.9 [29]. At pH values above pK3, erythrosin is a divalent anion, while below pK3 it is monovalent [12,29]. Photo-voltages observed on the 5-psec apparatus with 10 pM dye, pH ~5.5 inside, 3 outside, in 10 mM NaC1, has fast-part amplitudes (in mV) of: erythrosin (1.7), ethyl eosin (1.3), rose bengal (1.2), eosin Y (0.6), phloxine B (0.5), 4',5'-dibromofluorescein (0.3) and T,7'-dichlorofluorescein (0.1).…”