A photoelectric polarization photometer is described for the measurement of the polarization of the fluorescence of solutions. This instrument uses the principle that the linearly polarized component of the fluorescence vibrating in the direction of propagation of the exciting light is independent of the plane of polarization of the excitation and may be used to give a reference signal against which the signal given by the fluorescence component in the direction of vibration of the excitation may be compared. Positive and negative polarizations may be measured and actual measurements of solutions with ρ=0.003 to ρ=0.44 show the standard deviation of a measurement to be Δρ=±0.001. Analysis of the systematic errors involved indicates an absolute precision of equal magnitude. The absorption and re-emission of the fluorescence by the solutions results in changes of the polarization with concentration which are easily detected in the case of glycerol and water solutions of xanthydrol derivatives, where conditions are particularly favorable.
GREGORIO WEBER, "Photoelectric Method for the Measurement of the Polarization of the Fluorescence of Solutions," J. Opt. Soc. Am. 46, 962-970 (1956)