A cw dye laser with a rotatable intracavity Brewsterhyphen;angle plate can be forced to oscillate with its signal polarization rotated by an arbitrary angle bgr; about the laser axis from the pumping laser polarization. The threshold pump powerR(bgr;) then increases as the signal polarization is rotated from parallel (bgr; equals; 0deg;) to perpendicular (bgr; equals; 90deg;). By measuring the ratioR(90deg;)sol;R(0deg;) and comparing it with the first excited singlet level fluorescence intensity ratioI(0deg;)sol;I(90deg;) measured in the same laser medium below threshold, it is possible to determine the important dye laser triplet state parameterKTequiv;kSTtgr;Tsgr;Tsol;sgr;e. A detailed analysis of this new triplet measurement method is given. Both the orientational distribution of the excited state population and the gain for arbitrary polarizations and pumping geometry are calculated. Triplet state effects have been studied for Rhodamine 6G as a function of dye and soap concentration in H2O. The triplet state parameterKTis found to have the value 0.35 plusmn; 0.02 at 5960 Aring; for a 5 times; 10minus;4Mconcentration of R6G in water with 2percnt; by volume of Triton Xhyphen;100, and 0.25 plusmn; 0.02 for the same dye concentration with 4percnt; by volume of Ammonyx LO. The very long rotational relaxation times measured (sim; 1ndash;2 nsec) indicate rigid attachment of the R6G molecules to micelle soap complexes. Evidence of intermolecular energy transfer via dipolar coupling at higher dye concentrations is observed.
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