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Applications of Near Infra-red (NIR) and Far Infra Red and Advantages of NIR

  Some Important IR Regions:

ü Near-IR region:  4,000 cm–1 - 13000 cm–1.

ü Mid-IR region: 670-4000 cm-1

Ø Functional group region: 1450 cm–1 - 4000 cm–1.

Ø Fingerprint region: 670 cm–1 - 1450 cm–1.

ü Far-IR region: 10 cm–1 - 670 cm–1 

 

Near Infra-red (NIR) Spectroscopy:

ü The near-IR extends from approximately 13,000 cm–1 - 4000 cm–1

ü The absorption bands in the near-infrared often are overtones and combination bands of these group frequencies (of O-H, C-H and N-H)

ü The instrumentation for NIR spectroscopy, both in transmission mode and in reflectance mode, is similar to that for UV/visible spectrometers and for mid-IR spectrometry.

 

Applications of NIR Spectroscopy

ü Near-infrared spectroscopy is used in astronomy for studying the atmospheres of various stars by detecting the vibrational and rotational signatures of molecules such as titanium oxide, cyanide, and carbon monoxide which further provide a clue towards the star's atmospheric composition

ü Widely used for quantitative analysis of foods, several commercial instruments are available for compositional analysis of foods using NIR spectroscopy. 

ü NIR is also used for various applications in agriculture like for detecting insect damage, for maintaining fruit quality by excluding internally damaged fruits, moisture determination

ü NIR is also used in Pharmaceuticals industry for determining dosage forms for various pharmaceuticals, process monitoring like packaging, for detecting adulteration in food products.

Advantages of NIR over Mid-IR or Far-IR:

ü A major advantage of NIR spectroscopy is its ability to measure directly the composition of solid food products by use of diffuse reflection techniques.

ü Compared to mid-IR, the NIR is more useful for a quantitative analysis of aqueous samples because the OH absorption bands are much weaker. }

 

Far IR (Infra-Red) Spectroscopy

ü The far-IR extends from approximately 670 cm–1 - 10 cm–1 

ü FIR spectroscopy finds applications in the analysis of materials that include metals, including metal oxides, metal sulfides, and metal-ligand complexes.

ü FIR spectroscopy has also been applied to the analysis of polyamides, peptides, and proteins.

ü Because the FIR merges into the microwave region, it also finds use in the analysis of the rotational energies of gases.


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