Measurement of Optical Properties

Several experimental techniques may be used, such as acid/base titration, electrical conductivity measurement, temperature measurement, or measurement of optical properties such as refractive index, light absorption, and so on. In each case, it is necessary to specify the manner of tracer addition, the position and number of recording stations, the sample volume of the detection system, and the criteria used in locating the end-point. Each of these factors will influence the measured value of mixing time, and therefore care must be exercised in comparing results from different investigations. 

When solids react, we would like to know at what temperature the solid state reaction takes place. If the solid decomposes to a different composition, or phase, we would like to have this knowledge so that we can predict and use that knowledge In preparation of desired materials. Sometimes, intermediate compounds form before the final phase. In this chapter, we will detail some of the measurements used to characterize the solid state and methods used to foUow solid state reactions. This will consist of various types of thermal analysis (TA), including differentlEd thermal analysis (DTA), thermogravimetric analysis (TGA) and measurements of optical properties. 

Concentration profiting uses on- or in-line measurements of optical properties, typically not done for the whole volume, but along lines such as the channel cross-section (see e.g. [20]). Concentrations are accessible by photometric, electric or fluorescence measurements. Furthermore, vibrational analysis such as IR and Raman spectroscopy can be used for the same task [80,81]. Concentration profiling can also be achieved simply by gray-scale or comparable image analysis for quantitative data extraction from microscopy images of colored flows [20, 37, 68],... 

Research presented here was conducted in the context of the author s PhD thesis under supervision of her doctoral advisor Prof. Dr. K. Al-Shamery (University of Oldenburg). Organic synthesis was done under supervision of Prof. Dr. Arne Liitzen (University of Bonn), and growth and measurements of optical properties under supervision of Prof. Dr. H.-G. Rubahn (University of Southern Denmark, Sonderborg www.nanosyd.sdu.dk). 

As a final topic in this Section on the MEASUREMENT OF OPTICAL PROPERTIES OF PHOSPHORS, let us consider the following diagram, given as 6.7.35. on the next page. 

Selecting, combining and matching colors is a complicated art that only well-trained individuals are able to perform correctly. There are hundreds of different colorants used in the plastic industry, and there are as many types of colorants as different applications for plastics. Similarly to measurement of optical properties of paper and paperboard, the characterization of a color for plastics is based on the measurement of color (hue), brightness, and opacity. Other important variables to be considered in colorant selection include dispersability in the plastic, migration, toxicity, light stability, and chemical resistance. 

A photometric (or optical) sensor can be described as a device which can be employed for the detection and determination of physical and chemical parameters through measurements of optical property. Optical methods have played a dominant role and continue... 

Ellipsometry is an experimental technique employed primarily for measurements of optical spectra of highly absorbing solids and of surface films on solid or liquid substrates. It is used mostly in a reflection mode. In electrochemical interfacial systems, the main use of ellipsometry has been for measurement of optical properties and the thickness of surface films formed on the electrode surface. These observations complement other interfacial information (e.g. electric charge associated with film growth, changes in interfacial capacitance following growth of film and impedance associated with the film conversion process). 

The characterizahon of nanosilica incorporates many convenhonal microscopic and analytical methods. The details of such methods, the parameters that can be determined with them, and the associated references are summarized in Table 2.2. The main parameters to be identified are the morphology, surface characterizahon and measurement of optical properties of either the sihca core or the surfactants. Although, in order to produce specific nanosilica, a good knowledge of these methods and other novel techniques is clearly required, they will not be described in great detail at this point. 

Full Spectral Method [32] The full spectral method is based on a comprehensive spectral characterization of all involved materials. This involves as first step the measurement of optical properties over a broad spectral range from IR to far UV alternatively, an ah initio band structure calculation is also possible. One possible approach is to measure reflectance over the whole frequency range using IR and VUV spectroscopy. The measured reflected amplitude TZ(hv) is used to obtain the so-called reflection phase (f)(hv) using the corresponding Kramers-Kronig relation... 

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