Thermooptic coefficient

If absorption by impurities and solvent can be neglected, the quantum yield of the solution can be taken as that of the dye (tjfj = Unfortunately, the precision with which thermooptic coefficients are known is inadequate for precise measurements of the quantum yield via Eqs. (6)-(9). To circumvent this problem, Brannon and Magde [19] suggested using a nonfluorescent compound as reference. Thus in addition to the sample, designated below by superscript s, the reference compound, denoted by a superscript r, is measured under the same conditions (solvent, temperature, etc.). For this reference P bs equals P,b, and by combining Eqs. (6b), (7a) and (9), the following expression for the quantum yield is obtained ... 

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