Effects Materials of Organic Materials on Fluorescence Intensity of Rhodamine 6 G in Aqueous Solution

Abstract

It is well known that Rhodamine 6 G(R 6 G) dimerizes in higher concentration range than 2.5 x 10^-4 mol dm^-3 in aqueous solution and its fluorescence fades remarkably. Adding some detergents or complex forming compounds to this R 6 G dimer solution, its fluorescence intensity recovers to the level of that in alchol solution. From application of Kasha's theory on the difference spectrum between R 6 G monomer and dimer, we have estimated that the distance between xanthene planes of R 6 G is 6.28 A and these planes form the cross angle 40° in dimer molecules (Fig.2). In the case of addition of detergents to R 6 G aqueous solution the variation of R 6 G fluorescence intensity implies that the process from dimer to monomer is R 6 G₂→ R 6 G₂. Det→R 6 G in micelle. On the other hand for cyclodextrins and their derivative s and others, it cannot be contended that the additives with the large equilibrium constant for R 6 G monomer solution affect on recovering of fluorescence intensity more effectively to the dimer solution.