Vibration near-infrared spectroscopy

Near-infrared Spectroscopy. Near-infrared spectroscopy (NIRS) uses that part of the electromagnetic spectrum between the visible and the infrared. This region has the advantage that the instrumentation is nearest to visible instrumentation. Signals in the near-infrared come not from the fundamental vibrations of molecules but from overtones. As... 

In short, near-infrared spectra arise from the same source as mid-range (or normal ) infrared spectroscopy vibrations, stretches, and rotations of atoms about a chemical bond. In a classical model of the vibrations between two atoms, Hooke s Law was used to provide a basis for the math. This equation gave the lowest or base energies that arise from a harmonic (diatomic) oscillator, namely ... 

E.A. DeThomas and P.J. Brimmer, Monochromators for near-infrared spectroscopy, in Handbook of Vibrational Spectroscopy, J.M. Chalmers and PR. Griffiths (eds), vol 1, John Wiley Sons, New York, 2002. 

Theory of near-infrared spectroscopy 3.2.7 Molecular vibrations... 

Kruzelecky, R.V. and Ghosh, A.K., Miniature Spectrometers. In Chalmers, J.M. and Griffiths, P.R. (eds), Handbook of Vibrational Spectroscopy, vol 1 John Wiley 8c Sons New York, 2002, pp. 423 35. Miller, C.E., Near-Infrared Spectroscopy of Synthetic and Industrial Samples. In Chalmers, J.M. and Griffiths, P.R. (eds), Handbook of Vibrational Spectroscopy, vol 1 John Wiley 8c Sons New York, 2002, pp. 196-211. 

Madejova, J., M. Pentrak, H. Palkova, and P. Komadel. 2009. Near-infrared spectroscopy A powerful tool in studies of acid-treated clay minerals. Vibrational Spectrosc. 49 211-218. 

Mills IM (1992) Understanding spectra of highly excited vibrational states. In Murray I, Cowe lA (eds) Making Light Work Advances in Near Infrared Spectroscopy. VCH, Weinheim Mink J, Keresztury G (1988) Croat Chem Acta 61 731... 

Schuder, M. D. and Nesbitt, D. J., High resolution near infrared spectroscopy ofHCl—DCl and DCl—HCl Relative binding energies, isomer conversion rates, and mode specific vibrational predissociation, J. Chem. Phys. 100,7250-7267 (1994). 

Willig and co-workers used near-infrared spectroscopy to measure excited-state interfacial electron transfer rates after pulsed light excitation of cis-Ru(dcb)2(NCS)2-Ti02 in vacuum from 20 to 295 K [208]. They reported that excited-state electron injection occurred in less than 25 fs, prior to the redistribution of the excited-state vibrational energy, and that the classical Gerischer model for electron injection was inappropriate for this process. They concluded that the injection reaction is controlled by the electronic tunneling barrier and by the escape of the initially prepared wave packet describing the hot electron from the reaction distance of the oxidized dye molecule. It appears that some sensitizer decomposition occurred in these studies as the transient spectrum was reported to be similar to that of the thermal oxidation product of m-Ru(dcb)2(NCS)2. 

Near-Infrared Spectroscopy. Near-infrared (NIR) spectroscopy is a technique that has been around for some time but, like NMR spectroscopy, has only recently been improved and developed for on-line applications. Near-infrared analysis (NIRA) is a nondestructive technique that is versatile in the sense that it allows many constituents to be analyzed simultaneously 112, 113). The NIR spectrum of a sample depends upon the anharmonic bond vibrations of the constituent molecules. This condition means that the temperature, moisture content, bonding changes, and concentrations of various components in the sample can be determined simultaneously. In addition, scattering by particles such as sand and clay in the sample also allows (in principle) the determination of particle size distributions by NIRA. Such analyses can be used to determine the size of droplets in oil-water emulsions. 

Small, V. Fritz, A. Wetzel, D. (2006). Chemical imaging of intact seeds with NIR focal plane array assists plant hreeding. Vibrational Spectroscopy Vol.42, N.2, pp. 215-221 Sorensen, L.K. (2009). Application of reflectance near infrared spectroscopy for bread analyses. Food Chemistry Vol.113, pp. 1318-1322 Stark, E.K. Luchter, K. (2003). Diversity in NIR Instrumentation, in Near Infrared Spectroscopy. Proceeding oh the 11th International Conference. NIR Publication, Chichester, UK, pp. 55-66... 

The vibration of the X—H group is large in amplitude because of the low atomic weight of hydrogen, and consequently, deviates appreciably from true harmonic motion. The overtone and combination bands are therefore relatively intense. The phenomena most studied with near-infrared spectroscopy have been intermolecular associations, the type most familiar to biochemists being hydrogen bonding. 

Shultz, C. P., Role of Near-Infrared Spectroscopy in MinimaUy Invasive Medical Diagnosis , in Handbook of Vibrational Spectroscopy, Vol. 5, Chalmers, J. M. and Griffiths, P. R. (Eds), Wiley,... 

Figure 8.14 Near-infrared spectra of four commercial spirits (a) Scotch whiskey (40% ethanol) (b) gin (47% ethanol) (c) vodka (50% ethanol) (d) Bourbon (55% ethanol) [12], From McClure, W. F. and Stanfield, D. L., Near-Infrared Spectroscopy of Biomaterials , in Handbook of Vibrational Spectroscopy, Vol. 1, Chalmers, J. M. and Griffiths, P. R. (Eds), pp. 212-225. Copyright 2002. John Wiley Sons Limited. Reproduced with permission.

Recently, other vibrational techniques have been used in the charactmza-tion of LDHs and the decomposition process, such as near-infrared spectroscopy (4000-8000 cm i) (311), Raman spectroscopy, and infrared emission spectroscopy (312,313). These new techniques offer more ways to investigate the structure and properties of LDHs. 

Principles of Molecular Vibrations for Near-Infrared Spectroscopy... 

PRINCIPLES OF MOLECULAR VIBRATIONS FOR NEAR-INFRARED SPECTROSCOPY... 

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