Spectral matching

Potential Surface Reaction Path Synthesis Spectral Matching Pipeline SilverScreen SPACFIL TUTSIM and FANSIM Windows WordPerfect ... 

The MWD total gamma ray tools cannot be calibrated in the standard pit, since they are too large. Their calibration in API units is difficult because it varies with the spectral content of the radiation. By spectral matching the MWD logs can be made to closely resemble the wireline logs. The logs which were recorded by the MWD companies in counts per second (cps) are now recorded in API units. 

Oxyluciferin. During the luminescence reaction catalyzed by luciferase, luciferin is converted into a fluorescent compound, oxyluciferin, accompanied by the emission of greenish-blue light that spectrally matches the fluorescence of oxyluciferin (Fig. 7.2.6). The absorption spectrum of oxyluciferin is shown in Figs. 7.2.1 and 7.2.2. 

Figure 13 FTIR library spectral match of the spectrum acquired from the dried white-colored paint sample (top) compared with a dried vinyl toluene alkyd reference sample (bottom).

Figures 61 and 62 show the ATR-FTIR spectra recorded from areas C and D, respectively, from the cross-section of catheter sample 2. The infrared spectra from both areas, C and D, are spectrally matched closest by a library spectrum of a polyethylene. (Both the recorded spectra show weak additional absorption bands in the region 1,700-1,500 cm-1.) The ATR-FTIR spectrum recorded from...

The aim of this tutorial is to present briefly some of the optoelectronic elements, which can be used for designing of the interfaces for FOCS. More details on optoelectronic devices can be found in the references6 8. Special attention is placed on the appropriate spectral matching of these elements in order to obtain a sensor exhibiting optimal measuring properties such as dynamic range, sensitivity etc. 

The basic layout of Raman sensors is similar to fluorescence probes. The common sensor form is that of a fibre optic probe, with excitation and collection fibres. As the excitation light comes from a monochromatic source no excitation filter is required, but a spectrally matched emission notch filter blocking the excitation wavelength is almost always part of the sensor head. 

The extent of homogeneous mixing of pharmaceutical components such as active drug and excipients has been studied by near-IR spectroscopy. In an application note from NIRSystems, Inc. [47], principal component analysis and spectral matching techniques were used to develop a near-IR technique/algorithm for determination of an optimal mixture based upon spectral comparison with a standard mixture. One advantage of this technique is the use of second-derivative spectroscopy techniques to remove any slight baseline differences due to particle size variations. 

After the spectral matching process has been completed, the list of compounds with the top matching daughter spectra are identified and retrieved for each daughter spectrum in the reference compound. The molecular structures of the compounds with best matching spectra are drawn and compared for common substructures. The common substructures yield candidate spectrum/substructure correlations. Additional compounds are then tested to confirm or modify each correlation. Once the daughter spectrum is correlated with one or more substructures, this daughter spectrum is stored in the spectrum data base and is linked to the associated substructures stored in the structure data base. 

The bottleneck in utilizing Raman shifted rapidly from data acquisition to data interpretation. Visual differentiation works well when polymorph spectra are dramatically different or when reference samples are available for comparison, but is poorly suited for automation, for spectrally similar polymorphs, or when the form was previously unknown [231]. Spectral match techniques, such as are used in spectral libraries, help with automation, but can have trouble when the reference library is too small. Easily automated clustering techniques, such as hierarchical cluster analysis (HCA) or PCA, group similar spectra and provide information on the degree of similarity within each group [223,230]. The techniques operate best on large data sets. As an alternative, researchers at Pfizer tested several different analysis of variance (ANOVA) techniques, along with descriptive statistics, to identify different polymorphs from measurements of Raman... 

Identification involves the confirmation of a certain chemical entity from its spectrum by matching against the components of a spectral library using an appropriate measure of similarity such as the correlation coefficient, also known as the spectral match value (SMV). SMV is the cosine of the angle formed by the vectors of the spectram for the sample and the average spectrum for each product included in the library. 

SMV spectral match value VCSEL vertical cavity surface-emitting... 

Fig. 3 Infrared optical transmission and reflection spectra of the samples shown in Fig. 2 the spectrally matching transmission dips and reflection peaks represent photonic stopgaps. Upper and lower plots correspond to upper and lower rows in Fig. 2...

As with PDA detection and the construction of UV libraries, computerized data systems are used for data collection and processing with mass spectral detection. Unlike UV spectra, however, mass spectra are much less dependent on experimental conditions. Thus, it is possible to purchase commercial libraries of mass spectra for spectral matching. Mass spectral data systems range from systems that record the spectra and produce conventional relative abundance bar charts for subsequent analysis to those... 

Several who joined the program were contributors others did not have the requisite background and in spite of enthusiasms were of little value. Dr. Robert L. Cohen was one of the contributors he had the job of selecting a HABI that was most effective with the commercially available filters that would be useful with our dual-response imaging system. He found the best spectral match was with CDM-HABI. 

Newer technology allows for opaque, translucent, transparent samples as well as multiple film thicknesses for both reflectance and transmittance measurements. The newer technology provides a spectral match (matches spectral curve of the sample at each wavelength across the visible spectrum 360-740 nm). The advantage of spectral matching is its ability to match both color and opacity from a single database. 

Today, the speed of the Pentium processors has allowed for much more complicated algorithms written on the Windows platform, such as computing many-flux calculations and spectral matching routines. New color-matching technology provides sophisticated and intuitive color formulation that is easily learned and used by the expert as well as the novice color matcher. 

Computations are completed through an iteration process. There is no exact tristimulus match, but a best-fit spectral curve match is calculated. This is not a selective spectral match. Formulations are done using a spectral matching routine. 

Metamerism is minimized in calculations (spectral matching ensures quality under all lighting conditions, not just default conditions). 

Considering the full scope of many applications, traditional color matching has not provided a total solution for color matching. With the addition of the many-flux theory, and spectral matching, contemporary color-matching systems are the next step in providing a total solution for color formulation. 

Rectification and photovoltaic effects in organic p-n junctions were first reported by Kearns and Calvin [101] and by Meier [3]. The combination of rhodamines or triphenylmethane dyes (both n-type) with merocyanines or phthalocyanines (both p-type) generated photovoltages up to 200 mV and photocurrents of about 10 8 A at low light intensity, with power conversion efficiency much less than 1%. More recent studies have been performed on merocyanine and malachite green [89,90] and on phthalocyanines and TPyP (a porphyrin derivative) [102,103]. These devices showed stronger spectral sensitization and better spectral match to a solar spectrum than those of Schottky barrier cells using only one component. 

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