Forced Rayleigh scattering method measurement

The force Rayleigh scattering method was developed by Nagashima s group. Thermal diffusivity can be measured in a contact-free manner within a time interval of 1 ms, with a small temperature rise of 0.1 K and with a small volinne of about 10 mm The sample needs to be colored by an admixture of a dye for suitable absorption of a heating laser beam. The principle is schematically shown in Fig. 32. Two beams of equal intensity divided by means of abeam splitter cross in the sample to create... 

Experimental evidence was obtained showing that DT itself may be temperature dependent [109]. Another method to determine DT is the measurement of thermodiffusion in polymer solutions by forced Rayleigh light scattering [213]. This technique has the advantage that the employed temperature gradients are very small so that the coefficients are determined close to thermal equilibrium. 

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