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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 distribution of a compound between water and octanol is used to calculate the partition coefficient, P, of that molecule (often expressed as its logarithm to the base 10, log P). Water/octanol partitioning is a relatively good approximation of the partitioning between the cytosol and lipid membranes of living systems. [5]
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 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.
A vibration will be active in the IR if there is a change in the dipole moment of the molecule and if it has the same symmetry as one of the x, y, z coordinates. To determine which modes are IR active, the irreducible representation corresponding to x, y, and z are checked with the reducible representation of Γ vib. [4]
A simple and important member is 1-octanol, with an unbranched chain of carbons. Other commercially important octanols are 2-octanol and 2-ethylhexanol. Some octanols occur naturally in the form of esters in some essential oils. [1]
Infrared energy is emitted from a heated filament. By optically filtering the energy, the radiation spectrum is limited to the absorption band of the gas being measured. A detector measures the energy after the infrared energy has passed through the gas to be measured. This is compared to the energy at reference condition of no absorption.
1. An idyllic or picturesque place. 2. To function properly, these items require a vigorous, up-and-down motion before use. 3. A blending of names/terms to create something new. 4. The words in ...
The energy difference between gauche and anti is 0.9 kcal/mol associated with the strain energy of the gauche conformer. The anti conformer is, therefore, the most stable (≈ 0 kcal/mol). The three eclipsed conformations with dihedral angles of 0°, 120°, and 240° are transition states between conformers. [6]