Direct Observation of Picosecond Reorientation of Molecules in the Isotropic Phases of Nematogens

Lalanne, J. R.; Martin, Barbara Y.; Pouligny, B.; Kielich, S.

doi:10.1080/15421407708084503

Cited by 31 publications

(3 citation statements)

References 10 publications

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“…Beyond the mean-field approximation, or equivalently, beyond orientational relaxation through randomization of the pseudo-nematic domains with respect to each other, the interactions between the neighboring molecules result in a number of other modes of relaxation with much shorter orientational relaxation times, reflecting molecular orientational behavior from within the pseudo-nematic domains down to individual molecules. These relaxation modes exhibit no pretransitional behavior, and have been observed experimentally, both in the frequency domain [48] and time domain [49,50,54,61,56,57].…”

Section: Pure Lc Responsementioning

confidence: 99%

“…The strong host-host interaction makes the mean-field approximation inadequate for describing the rotational dynamics of liquid crystals in the isotropic phase. This topic in fact has received considerable interests, both theoretically and experimentally, over the last three decades [34,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60]. Though a complete understanding of the subject seems still missing [58,59,60], many salient features have been understood.…”

Section: Pure Lc Responsementioning

confidence: 99%

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Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Truong

2005

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Guest-host interaction has long been a subject of interest in many disciplines.Emphasis is often on how a small amount of guest substance could significantly affect the properties of a host material. This thesis describe our work in studying a guest-host effect where dye-doping of liquid crystalline materials greatly enhances the optical Kerr nonlinearity of the material. The dye molecules, upon excitation and via intermolecular interaction, provides an extra torque to reorient the host molecules, leading to the enhanced optical Kerr nonlinearity.We carried out a comprehensive study on the dynamics of the photoexcited dyedoped liquid crystalline medium. Using various experimental techniques, we separately characterized the dynamical responses of the relevant molecular species present in the 2 medium following photo-excitation, and thus were able to follow the transient process in which photo-excitation of the dye molecules exert through guest-host interaction a net torque on the host LC material, leading to the observed enhanced molecular reorientation.We also observed for the first time the enhanced reorientation in a pure liquid crystal system, where the guest population is created through photoexcitation of the host molecules them-

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Section: Pure Lc Responsementioning

confidence: 99%

Section: Pure Lc Responsementioning

confidence: 99%

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Truong

2005

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“…During recent decades, birefringence has been induced in fluid systems using the electric vector associated with an intense beam of light [1][2][3][4][5][6][7]. This phenomenon is strictly a third-order nonlinear optical effect and is the high-frequency analogue of the DC Kerr effect.…”

Section: Introductionmentioning

confidence: 99%

The laser-induced birefringence in nematogens; the influence of beam spatial and temporal profiles

Jennings¹,

Stone²

1997

Meas. Sci. Technol.

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Measurements of the laser-induced birefringence in the isotropic phase of nematogens close to the nematic - isotropic transition are of interest in the study of pre-transitional phenomena in liquid-crystalline systems. Hitherto, the variable spatial and temporal profile of the intensity of the laser beam as it traverses the sample has not been allowed for in the analyses and interpretation of experimental data. A theoretical analysis is presented of the output from a conventional crossed-polarizer apparatus which embraces the effect of these profile variances. Their influence on apparent data is accounted for in terms of the de Gennes pre-transitional theory for nematogens. Specific cases are discussed in which either fast or slow detection systems are used.

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Fast Molecular Reorientation in Liquid Crystals Probed by Nonlinear Optics

Lalanne

Buchert

Kielich

1993

Advances in Chemical Physics

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Direct Observation of Picosecond Reorientation of Molecules in the Isotropic Phases of Nematogens

Cited by 31 publications

References 10 publications

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

The laser-induced birefringence in nematogens; the influence of beam spatial and temporal profiles

Fast Molecular Reorientation in Liquid Crystals Probed by Nonlinear Optics

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