Rhodamine B as a probe for phase transition in liquid solutions

Local environment of fluorescent dyes could strongly affect emission dynamics of the latter. In particular, both signal intensities and emission lifetimes are highly sensitive to solvent temperatures. Here, temperature-dependent behavior Rhodamine B fluorescence in water and ethanol solutions was experimentally investigated. Phase transition point of liquid water to ice was shown to have a dramatic impact on both in intensity (30-fold drop) and in lifetime (from 2.68ns down to 0.13ns) of the dye luminescence along with the spectral shift of spectral maxima from 590 to 625nm. At the same time, ethanol solvent does not lead any similar behavior. The reported results and approaches enable further investigations of dye-solvent interactions and studies of physical properties of liquids at phase transition points.