title: Ultrafast fluorescence resonance energy transfer in a micelle.
abstract: Ultrafast fluorescence resonance energy transfer (FRET) from coumarin 153 (C153) to rhodamine 6G (R6G) is studied in a neutral PEO(20)-PPO(70)-PEO(20) triblock copolymer (P123) micelle and an anionic micelle (sodium dodecyl sulfate, SDS) using a femtosecond up-conversion setup. Time constants of FRET were determined from the rise time of the acceptor emission. It is shown that a micelle increases efficiency of FRET by holding the donor and the acceptor at a close distance (intramicellar FRET) and also by tuning the donor and acceptor energies. It is demonstrated that in the P123 micelle, intramicellar FRET (i.e., donor and acceptor in same micelle) occurs in 1.2 and 24 ps. In SDS micelle, there are two ultrafast components (0.7 and 13 ps) corresponding to intramicellar FRET. The role of diffusion is found to be minor in the ultrafast components of FRET. We also detected a much longer component (1000 ps) for intramicellar FRET in the larger P123 micelle.
authors.affiliation: Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Kalyanasis
authors.initials: K
authors.lastname: Sahu
authors.forename: Subhadip
authors.initials: S
authors.lastname: Ghosh
authors.forename: Sudip Kumar
authors.initials: SK
authors.lastname: Mondal
authors.forename: Bankim Chandra
authors.initials: BC
authors.lastname: Ghosh
authors.forename: Pratik
authors.initials: P
authors.lastname: Sen
authors.forename: Durba
authors.initials: D
authors.lastname: Roy
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D000042:Absorption; D016880:Anisotropy; D002627:Chemistry, Physical / Q000379:methods*; D003374:Coumarins / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D008823:Micelles; D008956:Models, Chemical; D015233:Models, Statistical; D011108:Polymers; D012235:Rhodamines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013997:Time Factors
chemical_list: D003374:Coumarins; D008823:Micelles; D011108:Polymers; D012235:Rhodamines; C488877:coumarin 153; C026188:rhodamine 6G