Picosecond Resonant Energy Transfer Studies of Aqueous Anionic Micellar Solutions

Article abstract of DOI:10.1021/j100319a032

Time-resolved resonant energy transfer between donor (rhodamine 6G) and acceptor (malachite green) dye molecules solubilized in micelles is used to study micellar size and shape.Single-photon counting or frequency-conversion optical gating provides our picosecond time profile.The dyes are solubilized at the spherical surface of sodium dodecyl sulfate micelles.At 0.3 M NaCl, the aggregation number N = 118, with the fits being extremely sensitive to micelle size, shape, and solubilization location of the dyes.Resonant energy transfer is also applied to aqueous solutions of ethoxylated sulfonates.The aggregation number grows (from N ca. 40) with salt: the spherical micelles distort to flexible, polymeric micelles.The picosecond energy transfer provides direct evidence for this shape change.