Transmittance techniques

This section is primarily concerned with in situ UV-visible spectroscopy and, for the various reasons discussed in the section on electroreflectance, we shall confine the discussion to transmittance techniques. 

For liquid-liquid systems, drop-size distributions and coalescence frequencies can be measured by a flash photomicrographic method and a modified dye-light transmittance technique. Both of these methods are accurate... 

A problem that may be encountered when analyzing a solid sample by transmittance spectroscopy is radiation scattering. Employing reflectance spectroscopy can sometimes reduce this problem. With this technique, the infrared spectra of most solid materials are easily obtained with little or no sample preparation. Spectra of a wide range of solid samples can be characterized with this technique, such as coatings on beverage containers and silicon wafers, polymer films, or other intractable samples. The reflectance technique, however, is less sensitive than the transmittance technique since about 80 /o of the infrared radiation is lost after being reflected off the sample surface. 

S.l II.0 0.05-0.40 5.67t25.0 — TUrbine Addition of dye in conjunction with light transmittance techniques... 

Rapid non-destructive methods for measuring oil percentage based on nuclear magnetic resonance have made selection for oil percentage much simpler. Infrared reflectance and transmittance techniques can be used for both oil and protein percentages (Hammond, 1991). 

Spedfle Inteifadal area and drop dze Interfacial area in extraction vessels has been measured most generally by a light-transmittance technique [10]. It varies considerably with location in the vessel [58, 81]. Intense turbulence at the impeller tip results in small drop sizes there, and a is consequently large. The drops coalesce as they flow to the more quiescent regions removed from the impeller, and... 

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