Generation of light

Laser light is produced from transitions between atomic or molecular energy levels. Generation of light requires two energy levels, E and E separated by the photon energy E of the light that is to be produced. 

Fireworks displays are fascinating to watch. Neon lights and sodium vapor lamps can transform the skyline of a city with their brilliant colors. The eerie phenomenon of the aurora borealis is an unforgettable experience when you see it for the first time. All of these events relate to the generation of light and its transmission through space. 

The elements of the p block are so rich in properties that it is hardly surprising that they are used to fabricate compounds with unusual and technologically exciting properties. Here we focus on two applications the generation of light and the emerging world of nanotechnology. 

Figure 5.12. Generation of light from luminol and lucigenin (a) shows the oxidation of lu-minol to generate light, whereas (b) shows light production from the oxidation of lucigenin hv represents a photon.

Kleinman, D. A., Ashkin, A., and Boyd, G. D. 1966. Second-harmonic generation of light by focused laser beams. Phys. Rev. 145 338-79. 

After an overview of the main papers devoted to chaos in lasers (Section I.A) and in nonlinear optical processes (Section I.B), we present a more detailed analysis of dynamics in a process of second-harmonic generation of light (Section II) as well as in Kerr oscillators (Section III). The last case we consider particularly in the context of coupled nonlinear systems. Finally, we present a cumulant approach to the problem of quantum corrections to the classical dynamics in second-harmonic generation and Kerr processes (Section IV). 

Second-harmonic generation of light is a nonlinear phenomenon in which chaotic behavior was discovered in 1983 [83] (for details, see Secction ). In the Kerr effect with an external time-dependent pump, a chaotic output may also occur, which was proved for the first time in 1990 by Milbum [84] (see also Section III). 

Nijland and J. Schroeder, The Generation of Light by Chemical Reactions in Flashlamps , Proceedings of the Eleventh International Symposium on Combustion, 1277-1284 (1966)... 

Generation of Light Hydrocarbons and Establishment of Normal Paraffin Preferences in Crude Oils... 

Figure 3. Generation of light hydrocarbons with depth in Beaufort Basin, N.W.T. Canada (based on a representative gas-cuttings log)...

Chemiluminescence The generation of light as a result of a chemical reaction. 

Characterization of Molecular Hyperpolarizabilities Using Third Harmonic Generation. Third harmonic generation (THG) is the generation of light at frequency 3co by the nonlinear interaction of a material and a fundamental laser field at frequency co. The process involves the third-order susceptibility x 3K-3 , , ) where —3 represents an output photon at 3 and the three s stand for the three input photons at . Since x(3) is a fourth (even) rank tensor property it can be nonzero for all material symmetry classes including isotropic media. This is easy to see since the components of x(3) transform like products of four spatial coordinates, e.g. x4 or x2y2. There are 21 components that are even under an inversion operation and thus can be nonzero in an isotropic medium. Since some of the terms are interrelated there are only four independent terms for the isotropic case. 

If we start with excited molecules or atoms, we can observe spontaneous emission— generation of light as the atom or molecule drops down to a lower energy level. Equation 8.1 also dictates the possible frequencies in the emission spectrum. Spontaneous emission in general gives radiation in all directions, and the selection rules are almost the same as in Equation 8.4. The only difference is that we must have An < 0 for the final state to be lower in energy than the initial state. 

Dixon and Schuster (1979, 1981) have investigated both the thermal and electron-donor induced reactions of 1-phenylethyl peroxyacetate [28] and a series of substituted 1-phenylethyl peroxybenzoates [29a-29e]. They report the direct generation of electronically excited states from unimolecular thermo-lyses, as well as generation of light by the chemically initiated electron-exchange luminescence mechanism. 

Elect regenerated chemiluminescence (ECL) — (-> electrochemiluminescence or electrochemically generated chemiluminescence) The generation of light in an electrochemical cell by an energetic electron transfer reaction, often between radical ions in an aprotic solvent. In a typical experiment in a solution of rubrene (R) and N,N,N, N -tetramethyl-p-phenylenediamine (TMPD) in dimethylformamide initially radical anions of rubrene are formed by electroreduction... 

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