RED EDGE PHOTOPHYSICS OF ETHANOLIC RHODAMINE-101 AND THE OBSERVATION OF LASER COOLING IN THE CONDENSED-PHASE

Laser cooling in fluid solutions of the laser dye rhodamine 101 in aci dified 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. T he most efficient cooling is achieved when the laser is tuned to 615 n m when a net cooling power of 0.37 mW per 100 mW of pumping power is o bserved. In this paper, details leading up to this unique observation are documented: in particular, the quantum efficiencies in highly conc entrated solutions and the characterization of anti-Stokes fluorescenc e as a nonintrusive temperature sensor.