Dynamic Kerr effect

The dynamic Kerr effect (DKE) is the third-order analogue of the second-order Pockel s effect. DKE also gives rise to phase shifts given by... 

Dynamic image analysis systems, 18 147 Dynamic Kerr effect (DKE), 17 454 Dynamic light scattering (DLS), 20 381 in molecular weight determination,... 

Potma, E. O., de Boeij, W. R, and Wiersma, D. A. 2001. Eemtosecond dynamics of intracellular water probed with nonlinear optical Kerr effect microspectroscopy. Biophys. J. 80 3019-24. 

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. 

M. Maroncelli, V. P. Kumar and A. Papazyan, A simple interpretation of polar solvation dynamics, J. Phys. Chem., 97 (1993) 13-17 E. W. Castner, Jr. and M. Maroncelli, Solvent dynamics derived from optical Kerr effect, dielectric dispersion, and time-resolved Stokes shift measurements an empirical comparison, J. Mol. Liq., 77 (1998) 1-36. 

The usefulness of electrical response measurements of solutions is not limited to effects linear in applied field. Transient birefringence induced by polarizing electric fields (the transient or dynamic Kerr effect) has given valuable information about biopolymers in solution the effect must by symmetry be an even function of E(t), beginning with terms in E (t). In both cases, a response theory treatment of transient behavior meets with difficulties not encountered in linear problems, but recent progress in deriving correlation function expressions for such effects is described in III. 

This outline of the response theory has for simplicity been limited to molecules with axial symmetry of y and Aa and to the field on, field off cases, but can be extended in both respects without basic difficulties. Detailed comparisons with experiment have not yet been made, but it already is clear that Kerr effect relaxation data can now provide more valuable and better defined information about orientational dynamics of biopolymers and other molecules than was previously possible. With the increasing accuracy and time resolution of digital methods, it should be possible to study not only slow overall rotations of large molecules (microseconds or longer) but small conformational effects and small molecule reorientations on nano and picosecond time scales. Moreover, one can anticipate the possibilities, for simple problems at least, of extending response theory to other quadratic and higher order effects of strong electric fields on observable responses. 

An issue that has been explored is how the relative distribution of charge and mass affect the viscosity of an ionic liquid. Kobrak and Sandalow [183] pointed out that ionic dynamics are sensitive to the distance between the centers of charge and mass. Where these centers are separated, ionic rotation is coupled to Coulomb interactions with neighboring ions where the centers of charge and mass are the same, rotational motion is, in the lowest order description, decoupled from an applied electric field. This is significant, because the Kerr effect experiments and simulation studies noted in Section III. A imply a separation of time scales for ionic libration (fast) and translation (slow) in ILs. Ions in which charge and mass centers are displaced can respond rapidly to an applied electric field via libration. Time-dependent electric fields are generated by the motion of ions in the liquid... 

Fig. 14.2. Principle of filamentation. The beam first self-focuses and collapses due to the Kerr effect. Ionization at the non-linear focus then defocuses the beam. A dynamical balance establishes between both processes over distances much over the Rayleigh length...

The following section contains a more detailed treatment of the theory behind the nonresonant spectroscopy of liquids. This will be followed by a description of the experimental implementation and data analysis techniques for a common OKE scheme, optical-heterodyne-detected Raman-induced Kerr-effect spectroscopy (22). We will then discuss the application of this technique to the study of the temperature-dependent dynamics of simple liquids composed of symmetric-top molecules. 

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. 

Lotshaw WT, McMorrow D, Kalpouzos C, Kenney-Wallace GA. Femtosecond dynamics of the optical Kerr effect in liquid nitrobenzene and chlorobenzene. Chem Phys Lett 1987 136 323-328. 

Neelakandan M, Pant D, Quitevis EL. Structure and intermolecular dynamics of liquids femtosecond optical Kerr effect measurements in nonpolar fluorinated benzenes. J Phys Chem A 1997 101 2936-2945. 

Loughnane BJ, Scodiunu A, Farrer RA, Fourkas JT, Mohanty U. Exponential intermolecular dynamics in optical Kerr effect spectroscopy of small-molecule liquids. J Chem Phys 1999 111 2686-2694. 

Deuel HP, Cong P, Simon JD. Probing intermolecular dynamics in liquids by femtosecond optical Kerr effect spectroscopy effects of molecular symmetry. J Phys Chem 1994 98 12600-12608. 

Cong P, Deuel HP, Simon JD. Structure and dynamics of molecular liquids investigated by optical-heterodyne detected Raman-induced Kerr effect spectroscopy (OHD-RIKES). Chem Phys Eett 1995 240 72-78. 

Kamada K, Ueda M, Ohta K, Wang Y, Ushida K, Tominaga Y. Molecular dynamics of thiophene homologues investigated by femtosecond optical Kerr effect and low frequency Raman scattering spectroscopies. J Chem Phys 1998 109 10948-10957. 

Neelakandan M, Pant D, Quitevis EF. Reorientational and intermolecular dynamics in binary liquid mixtures of hexafluorobenzene and benzene femtosecond optical Kerr effect measurements. Chem Phys Fett 1997 265 283-292. 

Smith NA, Fin S, Meech SR, Yoshihara K. Ultrafast optical Kerr effect and solvation dynamics of liquid aniline. J Phys Chem A 1997 101 3641-3645. 

Castner Jr. EW, Maroncelli M. Solvent dynamics derived from optical Kerr effect, dielectric dispersion, and time-resolved Stokes shift measurements an empirical comparison. J Mol Liq 1998 77 1-36. 

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." ... 

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. ...

The dynamical behavior of molecular liquids is directly observed via femtosecond optical Kerr effect (OKE) measurement in the time domain. The signal intensity, 5oke( ")i obtained by the measurement using an optically heterodyne-detected (OHD) technique (mixing the OKE signal with a local oscillator) can be expressed in the form ... 

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. 

Appendix III Dynamic Kerr-Effect Response Linear Molecules... 

The approach developed may also be extended to treat all the other averages (P (cos i)))(t) characterizing orientational relaxation in fluids [43]. In particular, the evaluation of the average of the second-order Legendre polynomial (/Tfcos 0))(t) (e.g., this quantity describes the dynamic Kerr effect [8]) is given in Appendix III. 

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