Photophysics of Nile red in solution: Steady state spectroscopy

Abstract

Spectroscopic properties of Nile red (NR) in organic solvents, binary solvent mixtures have been studied. Remarkable shifts in the emission band positions have been observed as a function of the polarity of the medium. In solvent mixtures, these shifts can be explained by the process of specific solvation known as dielectric enrichment. The displacement of the fluorescence band was also measured as a function of temperature to obtain the thermochromic shifts (15 cm −1 K −1 in methyltetrahydrofuran and 13.8 cm −1 K −1 in butanol). Excited state dipole moments were calculated from these shifts.