Libration (from the Latin verb librare "to balance, to sway"; cf.libra "scales") is a type of reciprocating motion in which an object with a nearly fixed orientation repeatedly rotates slightly back and forth. In physics and chemistry, a molecule (or other group of atoms) can undergo libration if it is subject to external forces or constraints that restrict its orientation.
For example, in liquid water, any given water molecule is attracted to neighboring molecules, so that it has a preferred orientation and cannot freely rotate. (Of course, over time, the neighboring molecules move around and the preferred orientation changes.) However, it can undergo librational motions, which are measureable in an infrared absorption spectrum[1] and contribute to motional narrowing of other peaks, for instance the OH stretch.
Another example is a molecular crystal: Each molecular unit has a preferred orientation due to interactions with the nearby molecules, but they have librational modes corresponding to small rotations about this preferred orientation.[2]
Referencesedit
^James, DW; Armishaw, RF (1975). "Structure of aqueous solutions: Infrared spectra of the water librational mode in solutions of monovalent halides". Australian Journal of Chemistry. 28 (6): 1179. doi:10.1071/CH9751179.
^Chihara, Hideaki; Shinoda, Takako (1962). "Librational Motion in Diatomic Molecular Crystals". Journal of the Physical Society of Japan. 17 (9): 1395. Bibcode:1962JPSJ...17.1395C. doi:10.1143/JPSJ.17.1395.
This physical chemistry-related article is a stub. You can help Wikipedia by expanding it.
libration, molecule, libration, from, latin, verb, librare, balance, sway, libra, scales, type, reciprocating, motion, which, object, with, nearly, fixed, orientation, repeatedly, rotates, slightly, back, forth, physics, chemistry, molecule, other, group, atom. Libration from the Latin verb librare to balance to sway cf libra scales is a type of reciprocating motion in which an object with a nearly fixed orientation repeatedly rotates slightly back and forth In physics and chemistry a molecule or other group of atoms can undergo libration if it is subject to external forces or constraints that restrict its orientation A diatomic molecule experiencing libration For example in liquid water any given water molecule is attracted to neighboring molecules so that it has a preferred orientation and cannot freely rotate Of course over time the neighboring molecules move around and the preferred orientation changes However it can undergo librational motions which are measureable in an infrared absorption spectrum 1 and contribute to motional narrowing of other peaks for instance the OH stretch Another example is a molecular crystal Each molecular unit has a preferred orientation due to interactions with the nearby molecules but they have librational modes corresponding to small rotations about this preferred orientation 2 References edit James DW Armishaw RF 1975 Structure of aqueous solutions Infrared spectra of the water librational mode in solutions of monovalent halides Australian Journal of Chemistry 28 6 1179 doi 10 1071 CH9751179 Chihara Hideaki Shinoda Takako 1962 Librational Motion in Diatomic Molecular Crystals Journal of the Physical Society of Japan 17 9 1395 Bibcode 1962JPSJ 17 1395C doi 10 1143 JPSJ 17 1395 nbsp This physical chemistry related article is a stub You can help Wikipedia by expanding it vte nbsp This spectroscopy related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Libration molecule amp oldid 1098248502, wikipedia, wiki, book, books, library,
