High-pressure studies on AOT reverse micellar aggregate by fluorescence probe method

The effect of pressure on the aqueous core of a reverse micellar aggregate was investigated by using fluorescence probe method. Steady-state and time-dependent fluorescence spectra of a water-soluble probe molecule, coumarin 343 (C343), which was dissolved in the water-pool of AOT/n-heptane reverse micelle, were measured at high pressures. On addition of water, the size of the water-pool was systematically changed. In the case of smaller water-pool (w0<5), the fluorescence spectrum of C343 shows a marked red-shift with increasing pressure, while in the case of larger water-pool (10<w0), it is almost invariant. The pressure effect on the solvation dynamics is also highly dependent on the size of the water-pool.