The critical energy transfer distance (R0) is calculated by the following equation, where ?, n, and NA are the dipole orientation factor (assumed to be κ2 = 2/3), the refractive index of a medium, and the Avogadro number, respectively. is the fluo-rescence quantum yield of an energy transfer donor (i.e., RB+) and JD*A represents the spectral overlap between the fluorescence spectrum of RB+ and the absorption spectrum of MG+. See also ref. [13].

has been cited by the following article:

• TITLE: Donnan Electric Potential Dependence of Intraparticle Diffusion of Malachite Green in Single Cation Exchange Resin Particles: A Laser Trapping-Microspectroscopy Study

  AUTHORS: Nguyen M. Cuong, Shoji Ishizaka, Noboru Kitamura

  KEYWORDS: Donnan Electric Potential; Intraparticle Diffusion; Cation-Exchange Reaction; Single Microparticle; Laser Trapping-Microspectroscopy

  JOURNAL NAME: American Journal of Analytical Chemistry, Vol.3 No.3, March 28, 2012

  ABSTRACT: A laser trapping-microspectroscopy technique combined with excitation energy transfer from a fluorescent cationic dye (Rhodamine B, RB+) to a non-fluorescent cationic dye (Malachite Green, MG+) was employed to study pH effects on the diffusion coefficients of MG+ (D(MG+)) in single cation-exchange resin microparticles with the diameters of 16 μm. When RB+-pre-adsorbed resin particles were soaked in an aqueous MG+ solution, the RB+ fluorescence was quenched gradually with the soaking time. The time course of the quenching efficiency of RB+ by MG+ was then used to evaluate the D(MG+) value in the particle. The D(MG+) value increased from 1.1 × 10-11 to 4.3 × 10-11 cm2.s–1 on going the solu- tion pH value from 9 to 4. The results were explained reasonably by a Donnan electric potential model.