Heterodyned Kerr effect

Before melting and for some time after only the band at 625 cm of the AA [C4CiIm]+ cation was observed in the 600-630 cm i region. Gradually 603 cm i band due to the GA conformer became stronger. After about 10 min the AA/GA intensity ratio became constant. The interpretation [50] is that the rotational isomers do not interconvert momentarily at the molecular level. Most probably it involves a conversion of a larger local structure as a whole. The existence of such local structures of different rotamers has been found by optical heterodyne-detected Raman-induced Kerr-effect spectroscopy (OHD-RIKES) [82], Coherent anti-Stokes Raman scattering (CARS) [83],... 

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. 

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. 

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>. 

We have performed optically heterodyne-detected optical Kerr effect measurement for transparent liquids with ultrashort light pulses. In addition, the depolarized low-frequency light scattering measurement has been performed by means of a double monochromator and a high-resolution Sandercock-type tandem Fabry-Perot interferometer. The frequency response functions obtained from the both data have been directly compared. They agree perfectly for a wide frequency range. This result is the first experimental evidence for the equivalence between the time- and frequency-domain measurements. 

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 ... 

OHD-RIKES(Optical Heterodyne Detected Raman Induced Kerr Effect Spectroscopy)... 

A new technique to measure low-frequency spectra is optical-heterodyne-detected Raman-induced Kerr-effect spectroscopy (OHD-RIKES). A recent publication by Chang and Cast-ner contains references to previous work within this field [18]. OHD-RIKES is based on a four-wave mixing of femtosecond laser pulses. Spectra obtained by OHD-RIKES reflect the anisotropic part of the Raman polarizability. Thus, the information obtained by OHD-RIKES is very similar to that obtained by low-frequency Raman scattering in an scattering configuration. From a theoretical point of view, the spectral representation obtained from OHD-RIKES measurements corresponds to the I v) representation given in Eq. (3). In Fig. 4 is shown an OHD-RIKES spectrum of liquid A-methylformamide (NMF). In Fig. 5 are shown low-frequency Raman spectra of liquid NMF together with the R(i>),... 

OHD-OKE optical heterodyne-detected optical Kerr effect... 

Before going into the details of various materials and their third-order NLO properties, it would serve well to have an idea of the characterization techniques used for their study. To study the effect of the real part of third-order susceptibility, Z-scan measurements, degenerate four-wave mixing (DFWM), optical heterodyne detection of optical Kerr effect (OHD-OKE), and differential optical Kerr effect (DOKE) detection are employed. For the study of TPA, techniques such as nonlinear transmission (NLT) method, two-photon excited fluorescence (TPEF) method, and Z-scan measurements are used. The observables from the above-mentioned techniques vary depending on the inherent limitations of the technique. The nature of the light source employed like the central wavelength of the laser. 

K. A., Rogers, J.A. (1998). Optical heterodyne detection of laser-induced gratings. Opt. Lett. 23 1319-1321 Fecko,C.J.,Eaves, J.D.,Tokmakoff, A. (2002). Isotropic and anisotropic Raman scattering from molecular liquids measured by spatially masked optical Kerr effect spectroscopy. J. Chem. Phys. 117 1139-1154. 

Hu, Z. Huang, X. Armapureddy, H. V. R. Margulis, C. J. (2008). Molecular dynamics study of the temperatme-dependent optical Kerr effect spectra and intermolecular dynamics of room temperature ionic liquid 1-methoxyethylpyridinium dicyanoamide. Journal of Physical Chemistry B, 112, 7837-7849 Hunt, N. T. Jaye, A. A. Meech, S. R. (2007). Ultrafast dynamics in complex fluids observed through the ultrafast optically-heterodyne-detected optical-Kerr-effect (OHD-OKE), Physical Chemistry Chemical Physics, 9, 2167-2180 Hyun, B.-R. Dzyuba, S. V. Bartsch, R. A. Quitevis, E. L. (2002). Intermolecular dynamics of room-temperature ionic liquids femtosecond optical Kerr effect measurements on l-alkyl-3-ethylimidazoliinn bis((trifluoromethyl)sulfonyl)imides. Journal of Physical Chemistry A, 106, 7579-7585. 

Smith, N. A. Meech, S. R (2002). Optically-heterodyne-detected optical Kerr effect (OHD-OKE) applications in condensed phase dynamics. International Reviews in Physical Chemistry, 21,75-100... 

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