Optical Kerr effect studies

Loughnane BJ, Fourkas JT. Geometric effects in the dynamics of a nonwetting liquid in microconfinement an optical Kerr effect study of methyl iodide in nanoporous glasses. J Phys Chem B 1998 102 10288-10294. 

Quite vis EF, Neelakandan M. Femtosecond optical Kerr effect studies of liquid methyl iodide. J Phys Chem 1996 100 10005-10014. 

Bartolini, P., Eramo, R., Taschin, A. and Torre, R. (2007). A superheterodyne-detected optical-Kerr-effect study of supercooled water dynamics. In preparation. 

Tsuzuki, S. Tokuda, H. Hayamizu, K Watanabe, M. (2005). Magnitude and directionality of interaction in ion pairs of ionic liquids relationship with ionic conductivity. Journal of Physical Chemistry B, 109,16474-16481 Turton, D. A. Hunger, J. Stoppa, A. Hefter, G. Thoman, A. Walther, M. Buchner, R Wynne, K. (2009). Dynamics of imidazolium ionic liquids from a combined dielectric relaxation and optical Kerr effects study evidence for mesoscopac aggregation. Journal of the American Chemical Society, 131,11140-11146 Urahata, S. M. Ribeiro, M. C. C. (2005). Single particle dynamics in ionic liquids of 1-alkyl-3-methylimidazolium cations. Journal of Chemical Physics, 122,024511/1-9 Wang, Y. Voth, G. A. (2006). Tail aggregation and domain diffusion in ionic liquids. Journal of Physical Chemistry B, 110,18601-18608 Wasserscheid, P. Welton, T., Eds. (2008). Ionic Liquids in Synthesis, 2nd Ed., WILEY-VCH, ISBN 978-3-527-31239-9, Weinheim... 

Giraud, G., Gordon, C. M., Dunkin, 1. R., and Wynne, K., The effects of anion and cation substitution on the ultrafast solvent dynamics of ionic liquids A time-resolved optical Kerr-effect spectroscopic study, /. Chem. Phys., 119,464-477,2003. 

An increasingly important tool to determine the strain-induced anisotropy is MOKE (magneto-optical Kerr effect). In section 2 we mentioned already the calculations by Freeman et al. (1999). Experimentally, e.g. Ali and Watts (1999) (see also references therein) apply a bending device to induce strains in a controlled way, and determine the (local) curvature and the strains by optical interferometry or by direct measurement (stylus). The properties of the substrate are incorporated in a finite-element modelling calculation, thus allowing an absolute determination of the film properties. Compare also Stobiecki et al. (2000), who studied the strain induced anisotropy in FeB/Cu/FeB trilayers, using Kerr magnetometry (MOKE). 

Magnetic thin films of nickel-iron (usually deposited at an 80 20 composition by weight) exhibit a number of unusual properties, which have led to many experimental and theoretical studies, as well as to impoitant applications in binary storage and switching, magnetic amplifiers, and magneto-optical Kerr-effect displays,... 

In this study we suppose nonlinear organic material shows optical Kerr effect as n = n0+n2lEl2 and n2 = X<3)/(2n0). Moreover for simplification, we suppose the waveguides allow single mode propagations and TE polarization. After appropriate handling we get the following nonlinear coupled mode equations [ 12] ... 

A combination of molecular mechanics calculations and electric birefringence (electro-optical Kerr effect) measurements of group IVB aryl compounds has been used to study conformational effects in these molecules12731. 

Smith NA, Fin S, Meech SR, Shirota H, Yoshihara K. Ultrafast dynamics of liquid anilines studied by the optical Kerr effect. J Phys Chem A 1997 101 9578-9586. 

Femtosecond optical heterodyn-detected optical Kerr effect spectroscopy and low-frequency Raman spectroscopy were used to study the molecular dynamics of selenophene <1998JCP10948>. Femtosecond Kerr effect spectroscopy was also used to examine the third-order polarizabilities of furan, thiophene, and selenophene, which was found to increase from furan to thiophene to selenophene <1996CPL(263)215>. 

In the general case, electrostriction is not isotropic even in isotropic dielectrics a field-induced anisotropy of electrostriction appears and is perceptible also in measurements of the static" and optical" Kerr effects. This anisotropy of electrostriction is particularly apparent if the field acting on the dielectric is strong, such as the intense electromagnetic field of a light wave, in which case the time-dynamics of the electrostrictive effect have to be studied s arately." ... 

On the assumption of total symmetry of the tensor of third-order nonlinear polarizability c(— co coi, cog, cog), its non-zero and independent elements are the same as those of Table 12. Direct theoretical calculations of c = c(0 0,0,0) have been performed for the atoms of inert gases and some simple molecules. Values of the tensor elements = c(— cu cu, 0,0) have been determined for numerous molecules from static Kerr effect studies and values of c = c(— cd ot>,coi — col) from measurements of optical birefringence induced by laser li t. Measurements of second-harmonic generation by gases in the presence of a static electric field yield the tensor elements c " = c( — 2co co, to, 0), which can also be obtained from second-harmonic scattering in centro-symmetric liquids. The elements of the tensor c = c(— 3co co, co, co)... 

It is to be presumed that by using formulae (227)—(231) in determining the optical anisotropy of molecules of the solute, better agreement can be obtained between the optical anisotropy values derived by the method of Le Fevre et al. - from studies of the static Kerr effect and those derived by the method of Pacault, Bothorel, et al. - from intensity-depolarized Rayleigh scattering. Also, the latest measurements of the optical Kerr effect point to the possibility of achieving such agreement. 

Figure 3 presents a comparison of the non-equilibrium solvent response functions, Eq (1), for both the photoexcitation ("up") and non-adiabatic ("down") transitions (cf. Fig. 2). The two traces are markedly different the inertial component for the downwards transition is faster and accounts for a much larger total percentage of the total solvation response than that following photoexcitation. The solvent molecular motions underlying the upwards dynamics have been explored in detail in previous work, where it was also determined that the solvent response falls within the linear regime. Unfortunately, the relatively small amount of time the electron spends in the excited state prevents the calculation of the equilibrium excited state solvent response function due to poor statistics, leaving the matter of linear response for the downwards S(t) unresolved. Whether the radiationless transition obeys linear response or not, it is clear that the upward and downwards solvation response behave very differently, due in part to the very different equilibrium solvation structures of the ground and excited state species. Interestingly, the downwards S(t), with its much larger inertial component, resembles the aqueous solvation response computed in other simulation studies, and bears a striking similarity to that recently determined in experimental work based on a combination of depolarized Raman and optical Kerr effect data. ...

Hu Z H, Huang X H, Annapureddy H V R, et al. Molecular dynamics study of the temperature-dependent optical kerr effect spectra and intermolecular dynamics of room temperature ionic liquid 1-methox-yethylpyridinium dicyanoamide. /. Phys. Chem. B. 2008. 112, 7837-7849. 

Other Work on Water-Related Systems. Sonoda et al.61 have simulated a time-resolved optical Kerr effect experiment. In this model, which uses molecular dynamics to represent the behaviour of the extended medium, the principle intermolecular effects are generated by the dipole-induced-dipole (DID) mechanism, but the effect of the second order molecular response is also include through terms involving the static molecular / tensor, calculated by an MP2 method. Weber et al.6S have applied ab initio linear scaling response theory to water clusters. Skaf and Vechi69 have used MP2/6-311 ++ G(d,p) calculation of the a and y tensors of water and dimethylsulfoxide (DMSO) to carry out a molecular dynamics simulation of DMSO/Water mixtures. Frediani et al.70 have used a new development of the polarizable continuum model to study the polarizability of halides at the water/air interface. 

As the local electric field in the particles is enhanced at the SPR, the metal nonlinear optical response can be amplified as compared to the bulk solid one. Moreover, the intrinsic nonlinear properties of metals may themselves be modified by effects linked with electronic confinement. These interesting features have led an increasing number of people to devote their research to the study of nonlinear optical properties of nanocomposite media for about two decades. Tire third-order nonlinear response known as optical Kerr effect have been particularly investigated, both theoretically and experimentally. It results in the linear variation of both the refraction index and the absorption coefficient as a function of light intensity. These effects are usually measured by techniques employing pulsed lasers. 

Most of the studies devoted to the nonlinear optical properties of metal nanoparticles use the notation x (<>>) to refer to the susceptibility for the optical Kerr effect. Unless otherwise specified, we will also adopt this simplified designation in the following. Let us just recall that it corresponds, in fact, to an experimental situation where a unique plane wave, linearly polarized (or three plane waves with same polarization and frequency), generates the third-order nonlinear optical phenomenon in an isotropic medium at the same frequency, and that the susceptibility is a priori a complex quantity. 

Tlie usual experimental techniques developed to study the optical Kerr effect in materials have already been described in a preceding chapter of this book. We only mention here the methods which have especially been used for nanocomposite materials as colloidal solutions or thin films Degenerate four-wave mixing (DFWM) and optical phase conjugation, which provide the modulus of x only and may be completed by Interferometry techniques to get its phase as well, optical limiting, optical Kerr shutter, and z-scan, which is probably the most common technique used in recent years due to its ability to provide simultaneously the nonlinear refraction and absorption coefficients of the same sample point [118],... 

In this paper we review the linear and nonlinear optical properties studies performed on solutions or thin film of rotaxanes and catenanes. Tlte linear optical properties were studied by U V-Vis spectrometry and m-line techniques. Tlte nonlinear optical properties were studied by second (SHG) and third (THG) harmonic generation in thin films and by electro-optic Kerr effect measurements in solutions. 

The nonlinear optical properties of rotaxanes and catenanes were studied mainly by three techniques the optical second and third harmonic generation and the electro-optic Kerr effect. As already mentioned, the harmonic generation techniques give the fast, electronic in origin, molecular and bulk hyperpolarizabili-ties, whereas the electro-optic methods are sensitive to all effects which induce optical birefringence, such as e.g. the rotation of molecules. Therefore the last technique is very useful to study the rotational mobility of molecules and/or their parts. 

We have shown that the electro—optic Kerr effect in solution is a useful tool to study the relative motion of these molecules. We observed a strong birefringence at frequencies that correspond to the rate at which the molecular cycle pirouettes ... 

Niziol et al. review the linear and NLO properties of some catenanes and rotaxanes studied in solutions or tliln films. Techniques like UV-Vis spectrometry, second and tlilrd harmonic generation in thin films and electro-optic Kerr effects in solution have been employed. They review the synthesis and material processing of tlrese derivatives. Niziol et al. describe how the rotation rate of the macrocycle in catenane solutions is more than an order of magnitude larger than in rotaxanes. They comment on the factors on which the rate of rotation depends. This new class of molecules, with mobile subparts, is very likely to have useful applications including tire construction of synthetic molecular machines and all-optical switching elements. 

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