Nonlinear optical dichroism

Solution Solution Thin film Solution LB film (red) 

LB film(blue) Thin film(blue) Thin film (red) Thin film Thin film Thin film Thin film Thin film Thin film Thin film Gel red form Single crystal 

Single crystal LB film (blue) Thin film Oriented film Oriented film Thin film LB film Thin film Thin film Thin film Oriented thin film 

One photon One photon One photon One photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Two photon Three photon Three Three Three Three Three Three Three Three Three Three 

Thus no variation of transmitted intensity will be observed when rotating the sample along an axis parallel to the beam propagation direction. In THG the resultant harmonic field is given by 

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Optical properties of cyanines can be usefiil for both chiral substituents/environments and also third-order nonlinear optical properties in polymer films. Methine-chain substituted die arbo cyanines have been prepared from a chiral dialdehyde (S)-(+)-2-j -butylmalonaldehyde [127473-57-8] (79), where the chiral properties are introduced via the chiral j -butyl group on the central methine carbon of the pentamethine (die arbo cyanine) chromophore. For a nonchiral oxadicarbocyanine, the dimeric aggregate form of the dye shows circular dichroism when trapped in y-cyclodextrin (80). Attempts to prepare polymers with carbocyanine repeat units (linked by flexible chains) gave oligomers with only two or three repeat units (81). However, these materials... 

In order to describe the problems of the nonlinear optical response from biological systems, the question of chirality must be addressed. Linear circular dichroism (CD) has been investigated extensively for biological compounds and a wealth of data are available on... 

The systems discussed up to now all showed chiral susceptibilities that were of the same order of magnitude or smaller than the achiral susceptibility components. The system that we discuss in this section has chiral susceptibilities that dominate the nonlinear optical response.53 The material is a chiral helicenebisquinone derivative shown in Figure 9.22. In bulk samples, the nonracemic, but not the racemic, form of the material spontaneously organizes into long fibers clearly visible under an optical microscope. These fibers comprise columnar stacks of helicene molecules.54,55 Similar columnar stacks self-assemble in appropriate solvents, such as n-dodecane, when the concentration exceeds 1 mM. This association can be observed by a large increase in the circular dichroism (CD) of the solutions. 

Nonlinear optical activity phenomena arise at third-order and include intensity dependent contributions to optical rotation and circular dichroism, as well as a coherent form of Raman optical activity. The third-order observables are - like their linear analogs - pseudoscalars (scalars which change sign under parity) and require electric-dipole as well as magnetic-dipole transitions. Nonlinear optical activity is circular differential. 

In the case of degenerate four-wave mixing, i.e. m = m + u> — u>, a nonlocal may support nonlinear optical activity and thus intensity dependent contributions to optical rotation and circular dichroism [4, 13, 17-19]. In analogy to Eq. (8) we can include nonlinear optical activity phenomena by writing [4]. 

Every property of an interface that can be optically probed can, in principle, be measured with the SFA. This may include information obtainable from absorption spectroscopy [55], fluorescence, dichroism, birefringence, or nonlinear optics [43], some of which have already been realized. 

Various optoelectronic and related properties of polymers from mono-substituted acetylene monomers have been studied extensively, such as photoconductivity, nonlinear optical properties, photo and electroluminescence, electrochromism, liquid-crystalline structures, helical structures, and stimuli-responsiveness [2, 3, 6, 7]. It is noteworthy that helical structures and stimuli-responsiveness using the change of the helical structure have progressed considerably in this decade [20, 21]. Yashima s induced circular dichroism... 

J. Lu, L. Wu, L. Jing, X. Xu, X. Zhang, Synthesis, circular dichroism, and third-order nonlinear optical properties of optically active poiphyrin derivatives bearing four chiral citronellal moieties. Dyes Pigm. 94, 169-174 (2012)... 

Magnetic Circular Dichroism, Theory Nonlinear Optical Properties... 

See also Biomacromolecular Applications of Circular Dichroism and ORD Chiroptical Spectroscopy, Emission Theory Chiroptical Spectroscopy, General Theory Chiroptical Spectroscopy, Oriented Molecules and Anisotropic Systems Circularly Polarized Luminescence and Fluorescence Detected Circular Dichroism Light Sources and Optics Luminescence, Theory Nonlinear Optical Properties Vibrational CD Spectrometers Vibrational CD, Applications Vibrational CD, Theory. 

Especially for the application to biological relevant surfaces (e.g., adsorbed proteins) the sensitivity of polarized SHG to the chirality of the molecules (the "handedness" of their structures) is important (Verbiest et al. 1998). Recently, the second-order nonlinear optical analog to circular dichroism and optical rotatory dispersion spectroscopy has been successfully developed (Yee et al. 1994 Byers et al. 1994). 

Using the alternating deposition of the amphiphiles with a carboxyl substituent and arachidic add, noncentrosymmetric LB films (hetero Y-type) were prepared, and molecular orientation and second-order optical nonlinearity in the LB films were evaluated with the linear dichroism [4] and the second-harmonic generation (SHG) measurements, respectively. The SHG measurement procedure is mentioned in the section 1.3. 

The dielectric tensor describes the linear response of a material to an electric field. In many experiments, and particularly in optical rheometry, anisotropy in is the object of measurement. This anisotropy is manifested as birefringence and dichroism, two quantities that will be discussed in detail in Chapter 2. The nonlinear terms are responsible for such effects as second harmonic generation, electro-optic activity, and frequency tripling. These phenomena occur when certain criteria are met in the material properties, and at high values of field strength. 

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