Laser cooling in fluid solutions of the laser dye rhodamine 101 in acidified ethanol has been observed when the molecule is excited into the low-energy tail of the absorption spectrum, at energies in the region 585-1593 cm-1 lower in energy than the 0-0 band origin at 590 nm. The most efficient cooling is achieved when the laser is tuned to 615 nm when a net cooling power of 0.37 mW per 100 mW of pumping power is observed. In this paper, details leading up to this unique observation are documented: in particular, the quantum efficiencies in highly concentrated solutions and the characterization of anti-Stokes fluorescence as a nonintrusive temperature sensor.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry