Reflection data

Reflection data can be checked for completeness when made available to the PLATON validation software as an FCF file along with the CIF file. Inadequate data collection procedures may result in an incomplete survey of the reciprocal lattice. Data collection on a CCD or image-plate based diffractometer may require more than one scan in order to avoid a cusp of missing data.  

The analysis of the FCF reflection data for reflections with significantly larger 

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Of course the typical seismic trace has many hundreds of reflections in it, all the way down from the surface to the deepest times measured. These days, engineers and geologists prefer to see the seismic in terms of the acoustic impedance rather than reflection data and this can be obtained by inversion from the seismic volume. Aseismic volume is made up of hundreds of thousands of traces. 

Fig. 5. shows six ultrasonic reflection tomograms. Three of these are from the Plexiglas specimen (shown left) and three are from the AlSi-alloy (shown right). The tomograms are reconstructed from reflection data measured across the plane (b), (c) and (e), respectively. The dark regions indicate high reflectivity and represent specimen interfaces and discontinuities. 

Figure Bl.18.10. Scaimmg microscope in reflection the laser beam is focused on a spot on the object. The reflected light is collected and received by a broad-area sensor. By moving the stage, the object can be scaimed point by point and the corresponding reflection data used to construct the image. Instead of moving the stage, the illuminating laser beam can be used for scaiming.

Dielectric constants of metals, semiconductors and insulators can be detennined from ellipsometry measurements [38, 39]. Since the dielectric constant can vary depending on the way in which a fihn is grown, the measurement of accurate film thicknesses relies on having accurate values of the dielectric constant. One connnon procedure for detennining dielectric constants is by using a Kramers-Kronig analysis of spectroscopic reflectance data [39]. This method suffers from the series-tennination error as well as the difficulty of making corrections for the presence of overlayer contaminants. The ellipsometry method is for the most part free of both these sources of error and thus yields the most accurate values to date [39]. 

Dale, J.M., Klatt, L.N., "Principal Component Analysis of diffuse Near-Infrared Reflectance Data From Paper Currency", / /)/. Spec. 1989 (43) 1399-1405. 

Fig. 8. X-ray reflection diagram of a thin polystyrene film on float glass [160]. The reflectivity R is plotted against the glancing angle . The film is spin coated from solution. A model fit (dashed line) to the reflectivity data is also shown where the following parameters are obtained film thickness = 59.1 0.1 nm, interface roughness glass-polymer = 0.4 0.1 nm, surface roughness polymer-air = 0.6+1 nm, mean polymer density = 1.05 + 0.01 g/cm-3. The X-ray wavelength is 0.154nm...

Table 11. X-ray reflection data for -y-brass (CvuZna) and calculated electron densities.

Tarek et al. [388] studied a system with some similarities to the work of Bocker et al. described earlier—a monolayer of n-tetradecyltrimethylammonium bromide. They also used explicit representations of the water molecules in a slab orientation, with the mono-layer on either side, in a molecular dynamics simulation. Their goal was to model more disordered, liquid states, so they chose two larger molecular areas, 0.45 and 0.67 nm molecule Density profiles normal to the interface were calculated and compared to neutron reflectivity data, with good agreement reported. The hydrocarbon chains were seen as highly disordered, and the diffusion was seen at both areas, with a factor of about 2.5 increase from the smaller molecular area to the larger area. They report no evidence of a tendency for the chains to aggregate into ordered islands, so perhaps this work can be seen as a realistic computer simulation depiction of a monolayer in an LE state. 

Arai et al. (1997) also used reflectance to study iodide absorption on gold. Eigure 27.26 shows reflectance data for a gold electrode in various electrolytes. 

The conversion was highest for coals in a narrow Ro max range of between 0.65 - 0.70. Cudmore s data on Australian coals also appears to exhibit a maximum when reflectance data is plotted against conversion (8). It is difficult to interpret this data because of the large variation in the vitrinite and reactive semi-fusinite content of these coals. The reactivity of vitrinite and reactive semi-fusinite would be expected to vary with rank but to different degrees. For several of the lower rank coals vitrinite is only a minor component of the coal. 

Further study of this system is though desirable, preferably with diffuse reflectance data also, before a definitive assignment of all the spectral features can be made. 

Waves I and II in Figure 2.81(b) are due to the formation of Cu(I) and Cu(II) surface oxides. Subsequent reduction of these films occurs during the cathodic sweep to give waves III and IV. The points A to D represent the potentials at which reflectivity data were collected during the voltammetric scan. The potential was ramped at lOmV/s until one of these potentials was reached, at which the scan was stopped for the duration of the data acquisition. The spectrum collected at A represents the condition of the electrode surface... 

S. Zhang, B. Soller, and R. Micheels, Partial leastsquares modeling of near infrared reflectance data for noninvasive in-vivo determination of deep tissue pH. Appl. Spectroscopy 52, 400-406 (1998). 

Two objects with different spectral properties, i.e., variation in the slope of spectral reflectance curve of two bands, can be separable with the help of ratio images (Lillesand et al. 2007). In this study standard reflectance data of USGS Spectral Library and John Hopkins University spectral library (Available in ENVI) have been used. To enhance the dissimilarity between different rock types in the scene, plots with a higher reflectance were kept in the numerator and plots with low reflectance were kept in the denominator, while taking the band ratios. Using this approach, a ratio of 5/3 was taken for basalt, 7/3 for peridotite, and 4/2 for vegetation. 

Naes, T., Isaksson, T., Kowalski, B. R. Anal. Chem. 62, 1990, 664—673. Locally weighted regression and scatter correction for near-infrared reflectance data. 

The crystallographic data contain all the information about the data that were used for determining the model. The most important information is the resolution. This refers to the minimum d spacing (O Eq. 22.1) and indicates the smallest distance between two atoms that can be resolved, i.e., completely separated based on electron density. The table also contains space group (P2i2i2i) and unit-cell information along with the statistical measurements for the reflection data. 

Data Processing and Statistics. Linear, power, and exponential lines were fitted to the dust, trash, and reflectance data by standard regression methods. 

Table I, Kebulka-Munk Transformation of Detergency Reflectance Data to... 

Transmittance and reflectance data are used in color measurements. Transmittance spectra are used for liquid color measurements, while reflectance spectra are used on solid samples (powders, surfaces) and on opaque liquids (paint). A large number of color scales are in use today. Some are specific to a particular industry, while others enjoy broader application. The most common scales are the CIE L a b (Commission... 

Second, the emphasis on empirical modeling leads to chemometrics being a highly interfacial discipline, in that specific tools are often developed with specihc applications already in mind. For example, specific chemometric tools have been developed to align retention time axes in chromatograms [20] and to preprocess diffuse reflectance data [21]. In contrast, other disciplines, such as statistics, are associated with well-defined stand-alone tools (ANOVA, f-test, etc.) that can be applied to a wide array of different applications. One consequence of this interfacial property of chemometrics is that one must often sift through a very large toolbox of application-specific tools in order to find one that suits a particular application. 

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