NIR Technology
For applications such as pharmaceutical, food, agriculture and asbestos testing and screening, NIR (Near Infrared) spectroscopy is a proven technology that delivers clear results.
NIR is a spectroscopic method that uses the near-infrared region of the
electromagnetic spectrum and is based on overtones and combinations of
bond vibrations in molecules. Whether you're looking for
application-specific explanations or a general overview of how NIR
works, the sections below provide information to help you learn.
NIR Overview
In NIR spectroscopy, the unknown substance is illuminated with a
broad-spectrum (many wavelengths or frequencies) of near infrared light,
which can be absorbed, transmitted, reflected or scattered by the sample
of interest. The illumination is typically in the wavelength range of
0.8 to 2.5 microns (800 to 2500 nm). The light intensity as a function
of wavelength is measured before and after interacting with the sample,
and the diffuse reflectance, a combination of absorbance and scattering,
caused by the sample is calculated.
Light is absorbed in
varying amount by the sample at particular frequencies corresponding
to the combinations and overtones of vibrational frequencies of some
bonds of the molecules in the sample.
Specifically, the bond vibrations
between oxygen and hydrogen (OH), carbon and hydrogen (CH), and
nitrogen and hydrogen (NH) result in NIR absorbance bands.
NIR can typically penetrate much further into a sample than FTIR,
and unlike Raman, is not affected by fluorescence. Thus, although
NIR spectroscopy is not as chemically specific as Raman or FTIR, it
can be very useful in probing bulk material with little or no sample
preparation.
Applications
For more information, please contact sales.chemid@thermofisher.com.