Harmonic measurement

Since many of the aromatic polymers studied [e.g., poly(n-hexylphenylsilane)] are also quite rigid in solution and optical microscopy studies on concentrated solutions often show signs of long range order, a partially oriented sample of this material was prepared by shear flow extension. Third harmonic measurements at 1.064 /im on partially oriented films prepared in this... 

FIGURE 9.2 Handheld harmonic analyzer showing voltage leads and current probe for voltage and current harmonic measurements. (Photograph courtesy of Fluke.)... 

Following the worldwide effort to harmonize measurement capabilities among countries, as a consequence of the strong tendency of globalization of economies, the importance of implementing traceable chemical and other measurements has been recognized as one of the principal tasks of any NMI. 

Detailed information about the components of the second-order susceptibility y2)(-2w to, w) can be obtained from second harmonic measurements on well-defined samples such as single crystals or oriented thin films, the latter obtained by procedures such as the asymmetric Langmuir-Blodgett deposition technique or electric-field poling of NLO chromophore-doped polymers.31 In the case of single-crystal samples, the second harmonic is... 

Generally, the analysis of environmental pollutants is considered as a necessary expense that is performed solely if stated by law. With less expensive screening methods and automated modern equipment to analyze suspect samples, the cost of analysis will become much lower. Hence, the attitude towards QA would most probably be more positive and the analytical work much more reliable for the customers. This also strengthens the international competitiveness of European producers. The credibility of the entire monitoring chain (screening methods, reference and standardized methods, as well as CRMs for the quality control of these methods) lies in the adequacy and integration of all three levels of the system. The adequate development and validation of methods is a prerequisite for a harmonized measurement system [80]. 

For these classes of conjugated molecular and polymer structures, the principal property is that their nonreson-ant, nonlinear optical responses are dominated by ultrafast, virtual excitations of the ir-electron states. This was directly demonstrated by MNA (2-methyl-4-nitroaniline) single crystal measurements of macroscopic second order susceptibilities at do (j 3) and optical frequencies (13-1 ) and combined second harmonic measurements and theo-... 

Harmonic measurements did indicate a higher THD level at point B then at point A. 

This high glass transition temperature polymer exhibits large electrooptic coefficients, -14-35 pm fV. The second harmonic measurements indicate long-term stability of the dipole orientation (> 800h at 100 °C). 

Since 1920 numerous national standardization organizations (e.g., Australia - AS/NZS, Britain - BSI, France - NF, Germany - DIN, Japan -JIS, Korea - KATS, Switzerland - SN, USA - ASTM) have been created, followed by the international standards bodies European - EN, and International - ISO and lEC. The international organizations try to harmonize measurement procedures where possible. 

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