Nanosecond kinetics of phase separation in binary fluid studied by a combination of Laser-induced temperature jump and Forster Resonant Excitation Transfer probing

Abstract: A novel technique for studying the demixing of binary fluids with nanosecond time resolution at nanometer spatial resolution is demonstrated. Nanosecond kinetics of phase separation initial stages in the water/2,6-lutidine mixture studied through the combination of a laser-induced temperature jump, and Forster Resonant Excitation Transfer techniques. A pair of chromophores: 8-hydroxy-1,3,6-pyrenetrisulfonate (HPTS) and Coumarin 480 form a FRET pair in the uniform phase of the mixture and separate into the components of the mixture in the nonuniform phase. The temperature jump that brings the mixture into a nonuniform phase is performed by the mid-infrared laser pulse. The exponential growth stage of phase separation is in the 5 to 20 nanoseconds range. The demonstrated technique can be applied to a broad range of chemical and biological systems.