**Anharmonic** — An har*mon ic, a. [F. anharmonique, fr. Gr. an priv. + ? harmonic.] (Math.) Not harmonic. [1913 Webster] The {anharmonic function} or {anharmonic ratio} of four points abcd on a straight line is the quantity (ac/ad):(bc/bd), where the segments… … The Collaborative International Dictionary of English

**anharmonic ratio** — Anharmonic An har*mon ic, a. [F. anharmonique, fr. Gr. an priv. + ? harmonic.] (Math.) Not harmonic. [1913 Webster] The {anharmonic function} or {anharmonic ratio} of four points abcd on a straight line is the quantity (ac/ad):(bc/bd), where the… … The Collaborative International Dictionary of English

**Molecular vibration** — A molecular vibration occurs when atoms in a molecule are in periodic motion while the molecule as a whole has constant translational and rotational motion. The frequency of the periodic motion is known as a vibration frequency, and the typical… … Wikipedia

**spectroscopy** — spectroscopist /spek tros keuh pist/, n. /spek tros keuh pee, spek treuh skoh pee/, n. the science that deals with the use of the spectroscope and with spectrum analysis. [1865 70; SPECTRO + SCOPY] * * * Branch of analysis devoted to identifying… … Universalium

**Cross-ratio** — D is the harmonic conjugate of C with respect to A and B In geometry, the cross ratio, also called double ratio and anharmonic ratio, is a special number associated with an ordered quadruple of collinear points, particularly points on a… … Wikipedia

**Quartz crystal microbalance** — A quartz crystal microbalance (QCM) measures a mass per unit area by measuring the change in frequency of a quartz crystal resonator. The resonance is disturbed by the addition or removal of a small mass due to oxide growth/decay or film… … Wikipedia

**Morse theory** — Morse function redirects here. In another context, a Morse function can also mean an anharmonic oscillator: see Morse potential In differential topology, the techniques of Morse theory give a very direct way of analyzing the topology of a… … Wikipedia

**Two-photon absorption** — (TPA) is the simultaneous absorption of two photons of identical or different frequencies in order to excite a molecule from one state (usually the ground state) to a higher energy electronic state. The energy difference between the involved… … Wikipedia

**Harmonic oscillator** — This article is about the harmonic oscillator in classical mechanics. For its uses in quantum mechanics, see quantum harmonic oscillator. Classical mechanics … Wikipedia

**Matrix mechanics** — Quantum mechanics Uncertainty principle … Wikipedia