QUENCHING OF RHODAMINE-101 EMISSION IN METHANOL AND IN COLLOIDAL SUSPENSIONS OF LATEX-PARTICLES

The quenching of rhodamine 101 emission in methanol by triethylamine, N,N-dimethylaniline, diphenylamine, and N-methyldiphenylamine was attributed to electron transfer. The values of the rate constants, which range from 108 to 1010 M-1 s-1, are in agreement with theoretical predictions of electron transfer. A comparison is made between the redox processes in methanol and on the surface of hydrocarbon latex particles suspended in aqueous solution. The association constants for the equilibria of rhodamine 101 and diphenylamine between the latex and bulk solution are 3.0 × 104 and 1.6 × 104 M-1, respectively. The quenching efficiency of diphenylamine in solutions containing 17 to 98 ppm latex is 22-72-fold higher than that in the methanolic solution. The fluorescence lifetime of rhodamine 101 is 4 ns in methanol. The fluorescence quantum yields in methanol (φF = 0.99) and water (φF = 0.71) were also determined. The implications of these results to photochemical storage reactions are discussed. © 1979 American Chemical Society.