Linear and nonlinear optical properties

Dispersion of Linear and Nonlinear Optical Properties of Benzene An Ab Initio Time-Dependent Coupled-Perturbed Hartree-Fock Study Shashi P. Kama, Gautam B. Talapatra and Paras N. Prasad Journal of Chemical Physics 95 (1991) 5873-5881... 

Table 2. Linear and nonlinear optical properties of azobenzene dendrimers...

The asymmetrical D-ji-A dyes, often referred to as push-pull polyenes, are an additional class of cyanine-like molecules of interest. Due to their dipolar nature, the linear and nonlinear optical properties of this series of dyes can be strongly influenced by solvent polarity [84]. The structures of a series of such dyes (G19,... 

Except through the study of linear and nonlinear optical properties of molecular crystals, methods to determine the nature of / require evaluation of appropriate characteristics of... 

The linear and nonlinear optical properties of the conjugated polymeric crystals are reviewed. It is shown that the dimensionality of the rr-electron distribution and electron-phonon interaction drastically influence the order of magnitude and time response of these properties. The one-dimensional conjugated crystals show the strongest nonlinearities their response time is determined by the diffusion time of the intrinsic conjugation defects whose dynamics are described within the soliton picture. 

The linear and nonlinear optical properties of one-dimensional conjugated polymers contain a wealth of information closely related to the structure and dynamics of the ir-electron distribution and to their interaction with the lattice distorsions. The existing values of the nonlinear susceptibilities indicate that these materials are strong candidates for nonlinear optical devices in different applications. However their time response may be limited by the diffusion time of intrinsic conjugation defects and the electron-phonon coupling. Since these defects arise from competition of resonant chemical structures the possible remedy is to control this competition without affecting the delocalization. The understanding of the polymerisation process is consequently essential. 

This paper will review the linear and nonlinear optical properties of polydiacetylenes with an emphasis on our work with the nBCMU polymers. The following section will discuss material... 

Linear and nonlinear optical properties of a class of polydiacetylenes that can be grown as large area and controlled thickness thin films have been investigated. This involved an integrated research effort including monomer synthesis, thin film growth and new measurement techniques. 

Conjugated polyenes exhibit large linear and nonlinear optical properties due to the mobility of electrons in extended TT-orbital systems. Hence, this is another reason for the growing interest shown in these molecules in recent years2,79-89. 

The remaining sections outline recent findings on the optical properties of metal-dendrimer nano-composites. The sections have been organized into areas of interest related to the fabrication as well as photophysical properties of these new and important materials. The first section discusses some of the important issues concerning the fabrication of these novel materials and their chemical characterization. The second section discusses the linear and nonlinear optical properties of these materials. The third section provides details related to the ultrafast emission properties of gold- and silver-dendrimer nanocomposites. 

LINEAR AND NONLINEAR OPTICAL PROPERTIES IN METAL-DENDRIMER NANOCOMPOSITES... 

Nakanishi H, Katagi H (1998) Microcrystals of polydiacetylene derivatives and their linear and nonlinear optical properties. Supramol Sci 5 289-295... 

P. Ye and Y. R. Shen, Local field effect on linear and nonlinear optical properties of... 

The 2PA research in our group began in 1996, involving a number of facets, from fundamental to applications. This review summarizes about 10 years of research efforts on 2PA materials and appHcations in our group. The first section includes the design and synthesis of novel 2 PA chromophores and the chemistry involved in their preparation. The second section is concerned with the linear and nonlinear optical properties of these chromophores as well as their photodynamic behavior. In the last section, further optimization of the chromophores for several intriguing applications is discussed, as are the principles of these applications. 

Several organometallic moieties serving as acceptors and donors have been evaluated. Molecular crystals of stilbenes have been shown to be unusually active in second harmonic generation. The linear and nonlinear optical properties of 3-methyl-4-methoxy-4 -nitro-stilbene (MMONS) single crystals will be presented. 

S. Abe, Excitonic Effects in the Linear and Nonlinear Optical Properties of Conjugated Polymers, in N. S. Sariciftci (Ed.), Primary Photoexcitations in Conjugated Polymers, World Scientific, Singapore, 1997, p. 115. 

All the linear and nonlinear optical properties introduced above are therefore expressed in terms of linear, quadratic and cubic response functions. They can be computed with high efficiency using analytical response theory [9] with a variety of electronic structure models [8],... 

For the description of the linear and nonlinear optical properties of metallotetrapyrroles, TDDFT methods have proven [133-148] to be an excellent alternative to conventional highly correlated ab initio methods, such as SAC-CI, STEOM-CC, and CASPT2, for which these systems still represent a severe computational challenge, especially when transition metals, lanthanides or actinides are involved. The few highly correlated ab initio calculations dealing with the excited state properties of metallotetrapyrroles that have appeared to date only concern magnesium and zinc porphyrins and porphyrazines [149-151]. Application of TDDFT methods to the electronic spectroscopy of a variety of metallotetrapyrroles, including homoleptic and heteroleptic sandwiches, will be illustrated in this section. 

TDDFT methods have also been applied successfully to the description of the linear and nonlinear optical properties of heteroleptic sandwich complexes. The optical spectrum and the hyperpolarizability of Zr(OEP)(OEPz,) for which large first hyperpolarizabilities, /JSHG (SHG=second-harmonic generation) were measured in an electric field induced second-harmonic generation (EFISH) experiment [182], have been investigated by TDDFT methods [134]. The excitation energies and oscillator strengths calculated... 

The pz orbitals have not been used so far. They are antisymmetric perpendicular to the (x,y)-plane and therefore orthogonal to the above combined sp and sp2 orbitals. pz orbitals from neighboring atoms combine independently to form molecular orbitals with their wavefunction delocalized over many atoms. The corresponding electrons are the 7T-electrons, which dictate to a large extend the linear and nonlinear optical properties. 

Recently, Pt-TEE molecular scaffolding yielded PTA oligomers with [Pt(PEt3)2] as spacer units [44]. Both the linear and nonlinear optical properties of these compounds revealed an... 

The experimental techniques adopted to measure linear and nonlinear optical properties are quite different and must be discussed separately. In broad terms, linear properties can be measured using low intensity probes and high spectral resolution. They are usually understood in the frequency domain. Nonlinear responses on the contrary need very large intensities, typically achieved in short pulses, and are discussed in the time domain. In addition to these physical considerations, we have to remember that time-resolved spectroscopy and optical characterization usually require good optical quality samples, so our understanding of the physics of these materials is closely linked to their quality. 

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