Kurtz powder technique

Another technique for characterizing crystalline materials is the Kurtz powder technique (18). In this method, a sample is ground into a powder, spread into a thin layer, and irradiated with a laser beam. The intensity of the beam is compared with that of a known reference material, (quartz powder is often used) and conclusions are drawn. Before discussing the nature of those conclusions, the concept of bireffingent phase matching is discussed. 

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

The optical SHG effect was investigated using Kurtz powder technique. A Nd YAG laser was utilized to generate fundamental 1064nm light. Microcrystalline KDP served as the standard. The SHG signal was detected by a photomultiplier and read on an oscilloscope. The samples were put between two glass plates. 

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. 

Complexes of various donor-substituted alkynes, such as FcCH=CHC CPh with WTp COI Fc = ferrocenyl Tp" = hydridotris(3,5-dimethylpyrazolyl)borate, have been studied using powder SHG at 1,064 nm, but efficiencies were considerably less than that of urea the molecular NLO properties have not been studied. The isomers of (dppe)( 7 -C6o)M(CO)3 (M = Cr, Mo) show complex 2-scan (532, ns pulses) behavior which is not only due to electronic effects, but also due to excited-state processes. The inclusion complexes formed by several ( -ligand)Fe(CO)4 species with thiourea were subjected to the Kurtz-Perry powder technique, but none exceeded... 

In the case of bulk materials or films the second-order susceptibility values, can be obtained by means of the investigation of the SHG [1-3]. The Kurtz-Perry technique [33] is often used to compare the intensity of the SHG of a powder sample with that of a reference sample of known such as quartz or urea. Although this technique is limited (the magnitude of the response is also dependent on particle size), it is a simple and rapid method for screening a large number of powder materials. 

S. K. Kurtz, T. T. Perry, A powder technique for the evaluation of nonlinear optical materials. J. Appl. Phys. 

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. 

The ability of powdered complex to generate second harmonic radiation was demonstrated in the apparatus shown in Scheme 1. The technique is based on the method of Kurtz and Perry. A Nd-YAG laser is directed through an... 

An investigation was carried out on powders of Re, Pd, and Pt complexes with 2,2 -bipyridine, which exhibit modest second-order NLO activities as evidenced by the Kurtz technique [67]. A more extended investigation on the second-order NLO response of various Re Zn and Hg complexes with donor-substituted vinyl bipyridines (for examples, 6 and 7) was done by the EFISH technique, working at 1.34 pm incident wavelength [10, 68, 69]. 

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