The far-infrared, approximately 400–10 cm −1 (25–1,000 μm) has low energy and may be used for rotational spectroscopy and low frequency vibrations. ![]() The mid-infrared, approximately 4,000–400 cm −1 (2.5–25 μm) is generally used to study the fundamental vibrations and associated rotational–vibrational structure. The higher-energy near-IR, approximately 14,000–4,000 cm −1 (0.7–2.5 μm wavelength) can excite overtone or combination modes of molecular vibrations. ![]() The infrared portion of the electromagnetic spectrum is usually divided into three regions the near-, mid- and far- infrared, named for their relation to the visible spectrum. Two-dimensional IR is also possible as discussed below. A common laboratory instrument that uses this technique is a Fourier transform infrared (FTIR) spectrometer. Units of IR wavelength are commonly given in micrometers (formerly called "microns"), symbol μm, which are related to the wavenumber in a reciprocal way. Typical units of wavenumber used in IR spectra are reciprocal centimeters, with the symbol cm −1. frequency, wavenumber or wavelength on the horizontal axis. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. It can be used to characterize new materials or identify and verify known and unknown samples. ![]() It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. Infrared spectroscopy ( IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. Measurement of infrared radiation's interaction with matter OVIRS instrument of the OSIRIS-REx probe is a visible and infrared spectrometer
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