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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.
In the secondary structure of proteins, hydrogen bonds form between the backbone oxygens and amide hydrogens. When the spacing of the amino acid residues participating in a hydrogen bond occurs regularly between positions i and i + 4, an alpha helix is formed. When the spacing is less, between positions i and i + 3, then a 3 10 helix is formed.
The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency, wavenumber or wavelength on the horizontal ...
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.
The spectrum of ice is similar to that of liquid water, with peak maxima at 3400 cm −1 (2.941 μm), 3220 cm −1 (3.105 μm) and 1620 cm −1 (6.17 μm) [14] In both liquid water and ice clusters, low-frequency vibrations occur, which involve the stretching (TS) or bending (TB) of intermolecular hydrogen bonds (O–H•••O).
IRPD spectroscopy has been shown to use electron ionization, corona discharge, and electrospray ionization to obtain spectra of volatile and nonvolatile compounds. [2] [3] Ionized gases trapped in a mass spectrometer can be studied without the need of a solvent as in infrared spectroscopy. [4] Schematic diagram of infrared photodissociation ...
One line of research uses graph invariants for generating hydrogen bond topologies and predicting physical properties of water clusters and ice. The utility of graph invariants was shown in a study considering the (H 2 O) 6 cage and (H 2 O) 20 dodecahedron, which are associated with roughly the same oxygen atom arrangements as in the solid and ...