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Rotational transitions, in which the molecule gains a quantum of rotational energy. Atmospheric water vapour at ambient temperature and pressure gives rise to absorption in the far-infrared region of the spectrum, from about 200 cm −1 (50 μm) to longer wavelengths towards the microwave region.
Absorbance within range of 0.2 to 0.5 is ideal to maintain linearity in the Beer–Lambert law. If the radiation is especially intense, nonlinear optical processes can also cause variances. The main reason, however, is that the concentration dependence is in general non-linear and Beer's law is valid only under certain conditions as shown by ...
In his 1803 publication about the quantity of gases absorbed by water, [1] William Henry described the results of his experiments: … water takes up, of gas condensed by one, two, or more additional atmospheres, a quantity which, ordinarily compressed, would be equal to twice, thrice, &c. the volume absorbed under the common pressure of the atmosphere.
The absorption coefficient is fundamentally the product of a quantity of absorbers per unit volume, [cm −3], times an efficiency of absorption (area/absorber, [cm 2]). Several sources [ 2 ] [ 12 ] [ 3 ] replace nσ λ with k λ r , where k λ is the absorption coefficient per unit density and r is the density of the gas.
In biochemistry, the molar absorption coefficient of a protein at 280 nm depends almost exclusively on the number of aromatic residues, particularly tryptophan, and can be predicted from the sequence of amino acids. [6] Similarly, the molar absorption coefficient of nucleic acids at 260 nm can be predicted given the nucleotide sequence.
In the context of ozone shielding of ultraviolet light, absorption cross section is the ability of a molecule to absorb a photon of a particular wavelength and polarization. Analogously, in the context of nuclear engineering, it refers to the probability of a particle (usually a neutron ) being absorbed by a nucleus.
Absorption is a condition in which something takes in another substance. [1] In many processes important in technology, the chemical absorption is used in place of the physical process, e.g., absorption of carbon dioxide by sodium hydroxide – such acid-base processes do not follow the Nernst partition law (see: solubility).
Water is the chemical substance with chemical formula H 2 O; one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. [26] Water is a tasteless, odorless liquid at ambient temperature and pressure. Liquid water has weak absorption bands at wavelengths of around 750 nm which cause it to appear to have a blue color. [4]