Nonlinear optics molecular nonlinearity

Coordination and Organometallic Complexes as Second-order Nonlinear Optical Molecular Materials... 

Molecularlv Doped Thermotropic Liquid Crystalline Polymer. The idea of the nonlinear optical medium which is the subject of this paper results from a synthesis of the ideas of the discussion above and a few concepts from nonlinear optical molecular and crystal physics. As discusssed several places in this volume, it is known that certain classes of molecules exhibit tremendously enhanced second-order... 

The development of highly active third-order nonlinear optical materials is important for all-optical signal processing. In contrast to second-order nonlinear optical molecular systems, there are few rational strategies for optimizing the third-order nonlinear optical response of molecular materials. Unlike second-order materials, there exist no molecular symmetry restrictions for the observation of a third-order nonlinear optical response. It is the instantaneous... 

An analytical structure-(hyper)polarizability relationship based on a two-state description has also been derived [49]. In this model a parameter MIX is introduced that describes the mixture between the neutral and charge-separated resonance forms of donor-acceptor substituted conjugated molecules. This parameter can be directly related to BLA and can explain solvent effects on the molecular hyperpolarizabilities. NMR studies in solution (e.g. in CDCl3) can give an estimate of the BLA and therefore allow a direct correlation with the nonlinear optical experiments. A similar model introducing a resonance parameter c that can be related to the MIX parameter was also introduced to classify nonlinear optical molecular systems [50,51]. 

Memory devices (electrical, optical) Molecular electronics Nonlinear optics Packaging materials pH modulator Polymer/solid electrolytes Semiconducting devices p-n junctions, pho-tovoltaics, Schottky diodes, light-emitting diodes, transistors, etc. 

Technology is reaching a point, however, where the unique properties of polymers make them suitable not only for these so-called passive applications, but also for active applications, wherein the polymer plays an active role in the functioning of the device. Examples of such applications include nonlinear optics, molecular electronics, and conductors electronic... 

Wong, M.S. Pan. F. Bosch, M. Spreiter. R. Bosshard. C. Giinter, P. Gramlich. V. Novel electro-optic molecular crystals with ideal chromophoric orientation and large second-order nonlinearities. J. Opt. Soc. Am. B 1998. 15. 426-431. 

Although our theoretical understanding of relationship between the structure and the microscopic optical nonlinearity is rather limited, some features of structural requirejjents for nonlinear optical molecular materials have been identified. Since x the corresponding... 

The quantum chemical calculations of optical and nonlinear optic molecular parameters are an important step in designing new materials. However, adequate description of molecular optical parameters presents a challenge for contemporary quantum chemistry. The main problem in such calculations is the necessity of accounting for a significant part of the electron correlation effects. In the last decade the density functional theory (DFT) has been used for (hyperjpolarizability calculations (see for instance [45]). It allows the consideration of systems with extended sizes. However, the DFT calculations are known to produce significant errors in the evaluation of the optical properties of a -conjugated systems [8, 26, 83]. 

Le Moigne, J., Kajzar, R, and Thierry, A., Single orientation in poly(diacetylene) films for nonlinear optics. Molecular epitaxy of l,6-bis(9-carbazolyl)-2,4-hexayne on organic crystals. 

Plaquet, A, Guillaume, M., Champagne, B., Castet, F., Ducasse, L., Pozzo, J.L., and Rodriguez, V. (2008) In silico optimization of merocyanine-spiropyran compounds as second-order nonlinear optical molecular switches. Rhys. Chem. Chem. Phys., 10, 6223-6232. 

Plaquet, A., Champagne, B., and Castet, E (2014) nonlinear optical molecular switches for alkali ion identification. Molecules, 19, 10574-10586. 

Much of the previous section dealt with two-level systems. Real molecules, however, are not two-level systems for many purposes there are only two electronic states that participate, but each of these electronic states has many states corresponding to different quantum levels for vibration and rotation. A coherent femtosecond pulse has a bandwidth which may span many vibrational levels when the pulse impinges on the molecule it excites a coherent superposition of all tliese vibrational states—a vibrational wavepacket. In this section we deal with excitation by one or two femtosecond optical pulses, as well as continuous wave excitation in section A 1.6.4 we will use the concepts developed here to understand nonlinear molecular electronic spectroscopy. 

In order to describe the second-order nonlinear response from the interface of two centrosynnnetric media, the material system may be divided into tlnee regions the interface and the two bulk media. The interface is defined to be the transitional zone where the material properties—such as the electronic structure or molecular orientation of adsorbates—or the electromagnetic fields differ appreciably from the two bulk media. For most systems, this region occurs over a length scale of only a few Angstroms. With respect to the optical radiation, we can thus treat the nonlinearity of the interface as localized to a sheet of polarization. Fonnally, we can describe this sheet by a nonlinear dipole moment per unit area, -P ", which is related to a second-order bulk polarization by hy P - lx, y,r) = y. Flere z is the surface nonnal direction, and the... 

Many of the fiindamental physical and chemical processes at surfaces and interfaces occur on extremely fast time scales. For example, atomic and molecular motions take place on time scales as short as 100 fs, while surface electronic states may have lifetimes as short as 10 fs. With the dramatic recent advances in laser tecluiology, however, such time scales have become increasingly accessible. Surface nonlinear optics provides an attractive approach to capture such events directly in the time domain. Some examples of application of the method include probing the dynamics of melting on the time scale of phonon vibrations [82], photoisomerization of molecules [88], molecular dynamics of adsorbates [89, 90], interfacial solvent dynamics [91], transient band-flattening in semiconductors [92] and laser-induced desorption [93]. A review article discussing such time-resolved studies in metals can be found in... 

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