Interpretive spectroscopy

Factors affecting the integrity of spectroscopic data include the variations in sample chemistry, the variations in the physical condition of samples, and the variation in measurement conditions. Calibration data sets must represent several sample spaces to include compositional space, instrument space, and measurement or experimental condition space (e.g., sample handling and presentation spaces). Interpretive spectroscopy where spectra-structure correlations are understood is a key intellectual process in approaching spectroscopic measurements if one is to achieve an understanding in the X and Y relationships of these measurements. 

The mathematical pictures called "electron density maps" are used to determine molecular structures and the energy level diagrams are used to determine the energies of bond formation and to interpret spectroscopy data. 

Freeman SK (Ed), "Interpretive Spectroscopy", Reinhold, New York, Chapman, London, 1965. 

The following table illustrates the potential for SW-NIR measurements. The approximate band locations shown are based on spectra of pure, undiluted materials measured with a low-resolution dispersive instrument. Most of the data were extracted from spectra shown in the interpretive spectroscopy references at the conclusion of this chapter (see also Fig. 7). 

The exclusive use of chemometrics alone provides a weak basis for analytical science. When performing mnltivariate calibrations, analytically valid calibration models require a relationship between X (the instrument response data or spectral data) and Y (the reference data) probability tells us only if X and Y appear to be related. If no cause-effect relationship exists between X and Y, the analytical method will have no true predictive significance. Interpretation of NIR spectra provide the knowledge basis for understanding the cause-and-effect of molecular structure as it relates to specific types of absorptions in the NIR. Interpretive spectroscopy is a key intellectual process in approaching NIR measnrements if one is to achieve an analytical understanding of these measurements. This book represents onr best effort to provide the tools necessary for the analyst to interpret NIR spectra. 

Source Workman, J., Interpretive spectroscopy for near-infrared, Appl. Spectrosc. Revs. 31 (3) 251-320, 1996. With permission. 

FIGURE 1.14 Illustration of the discrete quanta potential energy curves (Eq, E, Ej, and so on.) for both strong and weakly bonded dipoles as = n+ hv. (From Workman, J., Interpretive spectroscopy for near-infrared, AppZ. Spectrosc. Revs., 31 (3) 251-320, 1996. With permission.)... 

Walton, P.H., Beginning Group Theory for Chemistry, Oxford University Press, Oxford, 1998. Workman, J. and Coates, J., Interpretive Spectroscopy for SW-NIR, The Pittsburgh Conference, No. 126, 1995. 

INTERPRETIVE SPECTROSCOPY OF ORGANIC COMPOUND SPECTRA FOR POLYMERS AND RUBBERS IN THE NIR REGION... 

Interpretive spectroscopy provides a basis for the establishment of cause-and-effect relationships between spectrometer response and the chemical properties of the samples. While many books available on NIR cover a range of applications and topics from a broad perspective, most of them barely touch on structure correlation and interpretation of spectra. The first, and arguably the only, book to tackle this intriguing and challenging area, Practical Guide to Interpretive Near-Infrared Spectroscopy presents the most detailed discussion of the subject to date. 

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