far-infrared spectroscopy

physics

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June 26, 2026

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Far-infrared spectroscopy is a technique that uses the electromagnetic spectrum between 10 and 400 inverse centimeters (cm⁻¹). This region is primarily associated with the internal vibrational motion of molecules. When molecules absorb far-infrared radiation, it causes their bonds to vibrate, similar to how stretching and bending motions occur.123

Each molecule has a unique set of vibrational frequencies, acting like a fingerprint to identify it. By analyzing which wavelengths of far-infrared radiation a substance absorbs, scientists can determine the types of bonds and functional groups present, thus deducing the molecule's structure. This technique is valuable for identifying unknown compounds and understanding molecular structures.13

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spectroscopy
Infrared spectroscopy
…mid-infrared (400–4,000 cm⁻¹), and the far infrared (10–400 cm⁻¹). With the development of Fourier-transform spectrometers, this distinction of areas has blurred and the more sophisticated instruments can cover from 10 to 25,000 cm⁻¹ by an interchange of source, beam splitter, detector, and sample cell.
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…mid-infrared (400–4,000 cm⁻¹), and the far infrared (10–400 cm⁻¹). With the development of Fourier-transform spectrometers, this distinction of areas has blurred and the more sophisticated instruments can cover from 10 to 25,000 cm⁻¹ by an interchange of source, beam splitter, detector, and sample cell.
Read More