Near infrared radiation spectroscopy

There is a real chance of a breakthrough of Raman spectroscopy in routine analytics. Excitation of Raman spectra by near-infrared radiation and recording with interferometers, followed by the Fourier transformation of the interferogram into a spectrum -the so-called NIR-FT-Raman technique - has made it possible to obtain Raman spectra of most samples uninhibited by fluorescence. In addition, the introduction of dispersive spectrometers with multi-channel detectors and the development of several varieties of Raman spectroscopy has made it possible to combine infrared and Raman spectroscopy whenever this appears to be advantageous. 

Near-infrared spectrometry The study of sample properties as a function of absorptions by near-infrared radiation. Sometimes the term spectroscopy is used, but spectroscopy is restricted to the study of the spectra. 

Although near-infrared radiation was discovered by Herschel in 1800, NIR spectroscopy has only recently become an established technique for process analysis [6, 7]. The increasing success and widespread application of NIR spectroscopy in this area is a result of several advantageous features and technical developments. 

Infrared drying Near-infrared spectroscopy Penetration of heat into the sample Specific absorption of near-infrared radiation (1400-1450,1920-1950 nm) by the water molecules of the food 10-25 min... 

It may be helpful to explain the use of the terms rare earths and lanthanides throughout the text. By convenience, the term lanthanides refers to the elements La (Z = 57) to Lu (Z = 71). The term rare earths is commonly used for the lanthanides with inclusion of the elements Y (Z = 39) and Sc (Z = 21). Although one speaks often about rare-earth spectroscopy, the term lanthanide spectroscopy is preferable. The main objects of study in lanthanide spectroscopy are the trivalent lanthanide ions from Ce (4f ) to Yb3+ (4f ), since these ions have unpaired f electrons and can interact with ultraviolet, visible or near-infrared radiation. Divalent ions like Eu " " have gained less interest and will not be discussed here. The trivalent lanthanide ions La " (4f ) and Lu (4f ) are not spectroscopically active, because of an empty or filled 4f shell. The same is true for and Sc. Yttrium, lanthanum and to a lesser extent lutetium compounds are used as transparent host crystals in which other trivalent lanthanide ions can be doped. The trivalent lanthanide ions can readily substitute for Y, La " and Lu. Expressions like point group of the rare-earth site and the crystal field in rare-earth compounds are thus meaningful. 

Near infrared spectroscopy (NIRS), a technique based on absorption and reflectance of monochromatographic radiation by samples over a wavelength range of 400-2500 run, has been successfully applied for food composition analysis, for food quality assessment, and in pharmaceutical production control. NIRS can be used to differentiate various samples via pattern recognitions. The technique is fast and nondestructive method that does not require sample preparation and is very simple to use compared too many other analytical methods such as HPLC. The drawback of NIRS, however, is that the instrument has to be calibrated using a set of samples typically 20-50 with known analyte concentrations obtained by suitable reference methods such as FIPLC in order to be used for quantitative analyses. Simultaneous quantification of the... 

Complementary to middle-IR spectroscopy but requires very little sample preparation since near-infrared (NIR) radiation with its good penetration properties can be used for the analysis... 

Although a number of secondary minerals have been predicted to form in weathered CCB materials, few have been positively identified by physical characterization methods. Secondary phases in CCB materials may be difficult or impossible to characterize due to their low abundance and small particle size. Conventional mineral identification methods such as X-ray diffraction (XRD) analysis fail to identify secondary phases that are less than 1-5% by weight of the CCB or are X-ray amorphous. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM), coupled with energy dispersive spectroscopy (EDS), can often identify phases not seen by XRD. Additional analytical methods used to characterize trace secondary phases include infrared (IR) spectroscopy, electron microprobe (EMP) analysis, differential thermal analysis (DTA), and various synchrotron radiation techniques (e.g., micro-XRD, X-ray absorption near-eidge spectroscopy [XANES], X-ray absorption fine-structure [XAFSJ). 

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