Kurtz powder technique, measurement

Fig. 5. Organometallic complexes with large xt2) measured by the Kurtz powder technique.

The Kurtz powder technique developed by S. W. Kurtz and T. T. Perry in 1968 offered the first possibility for the determination of nonlinear optical properties of crystalline organic componnds. In comparison with a standard such as quartz or urea, the capability of materials to generate the second harmonic is detected. The pulverized sample is irradiated by a laser and the intensity of frequency-doubled light is measured. As this method is influenced by many factors, such as particle size, it is only semi-quantitative. The results give no precise values for the hyperpolarizability p. A further disadvantage is that the method is limited to molecules that crystallize in noncentrosynunetric space groups. 

Predictive power is poor, so confine searches to easily preparable materials. Use early screening techniques which work on powders like dielectric constant measurements, the Giebe-Scheibe circuit for piezoelectricity and the Kurtz 36,37) powder measurement test for SHG which was "invented" as a result of our pleas for help in finding materials. 

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