Optical study of Xanthene type dyes in nano-confined liquid

Abstract

The optical activity of dye molecules in different environments is of great interest for<br><br>many applications such as laser system or biological imaging. We investigate the<br><br>fluorescence and absorption spectrum of nano-confined Xanthene dyes (Rhodamine<br><br>B and Fluorescein sodium salt) in a two-phase liquid. Each shows very distinct optical<br><br>behavior in the water phase of a reverse microemulsion. Their optical properties such<br><br>as absorption and fluorescence for different dye and nanodroplets concentration are<br><br>investigated. We show that for the same concentration of dye in the microemulsion the<br><br>peak of fluorescence intensity is varied by altering the concentration of nanodroplets.<br><br>However, the trend of the change is widely different depending on the hydrophobicity<br><br>of dyes. Quantum–mechanical second order perturbation theory is used to calculate<br><br>the ratio of dipole moments in the ground and exacted states, which accounts for<br><br>Stokes shift of fluorescence peak. Photon correlation spectroscopy is employed to<br><br>check the trace of dye in the oil phase of the microemulsion