Figure 1.

(a) Chemical structure of Nile Red. (b) Steady-state absorption and fluorescence spectra in solvents of different polarities: n-hexane and 1-pentanol. (c.i) E₀₀ energy and (c.ii) Stokes shifts extracted from steady-state data as a function of reaction field, f(ε,n), for Nile Red in 12 different solvents. E₀₀ was determined from the crossing point between the normalized absorption and fluorescence spectra to ensure consistency across all data sets.