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[1] [2] In physical and analytical chemistry, infrared spectroscopy (IR spectroscopy) is a technique used to identify chemical compounds based on the way infrared radiation is absorbed by the compound. The absorptions in this range do not apply only to bonds in organic molecules.
The infrared spectrum of a sample is recorded by passing a beam of infrared light through the sample. When the frequency of the IR matches the vibrational frequency of a bond or collection of bonds, absorption occurs. Examination of the transmitted light reveals how much energy was absorbed at each frequency (or wavelength).
Infrared signature, as used by defense scientists and the military, is the appearance of objects to infrared sensors. [1] An infrared signature depends on many factors, including the shape and size of the object, [2] temperature, [3] and emissivity, reflection of external sources (earthshine, sunshine, skyshine) from the object's surface, [4] the background against which it is viewed [5] and ...
In spectroscopy, an absorption band is a range of wavelengths, frequencies or energies in the electromagnetic spectrum that are characteristic of a particular transition from initial to final state in a substance. According to quantum mechanics, atoms and molecules can only hold certain defined quantities of energy, or exist in specific states. [1]
Example of a linear molecule. N atoms in a molecule have 3N degrees of freedom which constitute translations, rotations, and vibrations.For non-linear molecules, there are 3 degrees of freedom for translational (motion along the x, y, and z directions) and 3 degrees of freedom for rotational motion (rotations in R x, R y, and R z directions) for each atom.
Fourier transform infrared spectroscopy (FTIR) [1] is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas. An FTIR spectrometer simultaneously collects high-resolution spectral data over a wide spectral range.
A molecular vibration is a periodic motion of the atoms of a molecule relative to each other, such that the center of mass of the molecule remains unchanged. The typical vibrational frequencies range from less than 10 13 Hz to approximately 10 14 Hz, corresponding to wavenumbers of approximately 300 to 3000 cm −1 and wavelengths of approximately 30 to 3 μm.
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