Simulation of erasure of photoinduced anisotropy by circularly polarized light

Sajti, Sz.; Kerekes, Á.; Barabás, Miklós; Lőrincz, Emőke; Hvilsted, Søren; Ramanujam, P. S.

doi:10.1016/s0030-4018(01)01308-6

Cited by 17 publications

(21 citation statements)

References 5 publications

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“…By contrast to the mean field models of Refs. [7,8,21], it implies that the presence of long-living angular correlations is irrelevant for cis molecules. Certainly, this is the simplest case to start from before studying more complicated models.…”

Section: Discussionmentioning

confidence: 99%

“…We have already shown that these models include the mean field theories considered in Refs. [7,8,21]. …”

Section: Modelmentioning

confidence: 99%

“…In Refs. [7,8,21] this distribution has been assumed to be proportional to exp(−V (n)/k B T ), where V (n) is the mean-field potential that depends on the order parameter tensor.…”

Section: Modelmentioning

confidence: 99%

“…We use the results of general analysis to formulate a simple model of the photoinduced ordering in LC azopolymers. In addition to the long term stability of POA, this model accounts for biaxiality of the photoinduced orientational structures [4,17,18,19,20,21] that was neglected in the models of Refs. [7,8,10,11].…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of photoinduced anisotropy in azopolymers: models and mechanisms

Kiselev

2002

J. Phys.: Condens. Matter

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We consider the effect of photoinduced optical anisotropy (POA) in azopolymers. Using a unified approach to the kinetics of photo-reorientation we discuss the assumptions underlying the known theoretical models of POA and formulate a tractable phenomenological model in terms of angular redistribution probabilities and order parameter correlation functions. The model takes into account biaxiality effects and long term stability of POA in azopolymers. It predicts that under certain conditions two different mechanisms, photoorientation and photoselection, will dominate POA depending on the wavelength of pumping light. By using available experimental data, we employ the model to compute dependencies of principal absorption coefficients on the illumination time. Our calculations clearly indicate the different regimes of POA and the numerical results are found to be in good agreement with the experimental data.

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Section: Discussionmentioning

confidence: 99%

“…We have already shown that these models include the mean field theories considered in Refs. [7,8,21]. …”

Section: Modelmentioning

confidence: 99%

“…In Refs. [7,8,21] this distribution has been assumed to be proportional to exp(−V (n)/k B T ), where V (n) is the mean-field potential that depends on the order parameter tensor.…”

Section: Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of photoinduced anisotropy in azopolymers: models and mechanisms

Kiselev

2002

J. Phys.: Condens. Matter

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“…[52,53] In fact, it is known that chiral circularly polarised electromagnetic radiation is able to induce enantioselective conversion [54] and tends to align the azobenzene side groups along directions close to the light propagation. [14,55] It is possible that transfer of angular momentum from the CPL to the medium, as occurs when a CP photon is absorbed, induces a precession of the chromophores with a sense of rotation congruent to the sense of the CPL. This would mean that l-CPL induces a left-handed organisation of the azobenzene molecules, whereas r-CPL induces a right-handed one.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Supramolecular Chirality and Reversible Chiroptical Switching in New Chiral Liquid‐Crystal Azopolymers

Barberá

Giorgini

Paris

et al. 2008

Chemistry A European J

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The synthesis of chiral liquid-crystalline polymers of well-controlled structure (linear and three-armed star-shaped) with distinct average chain lengths and low polydispersity was achieved by atom transfer radical polymerisation (ATRP) of a new optically active monomer (S)-4-[6-(2-methacryloyloxypropanoyloxy)hexyloxy)]-4'-ethoxyazobenzene [(S)-ML6A], containing the L-lactic residue of one absolute configuration in the side-chain. All the obtained polymeric samples, characterised by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and polarised optical microscopy (POM), exhibit a smectic A(1/2) (fully interdigitated) liquid-crystalline phase and high cleaning points, with transition temperatures dependent on the average polymerisation degree and the macromolecular structure. The chirality originated at the molecular level by the asymmetric functionality of the L-lactic acid residue provides the polymers, in the smectic phase, of highly homogeneous conformations with a prevailing chirality related to the presence of H-aggregates having conformational dissymmetry of one prevailing screw-sense. By irradiating with circularly polarised light (CPL), it is possible to photomodulate the chiroptical properties of these intrinsically chiral polymeric thin films. Upon irradiation with left-handed CPL (l-CPL), the circular dichroism (CD) spectra of the films show enhancement of ellipticity and a net inversion of sign. The effect is reversible and the mirror image of the CD spectrum can be restored by pumping with right-handed CPL radiation (r-CPL). The results show the ability of l-CPL to invert the supramolecular chirality of the materials and demonstrate the essential role of azoaromatic aggregates.

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Deformation of amorphous azobenzene-containing polymer films induced by polarized light

2012

Acta Mech Sin

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Simulation of erasure of photoinduced anisotropy by circularly polarized light

Cited by 17 publications

References 5 publications

Kinetics of photoinduced anisotropy in azopolymers: models and mechanisms

Kinetics of photoinduced anisotropy in azopolymers: models and mechanisms

Supramolecular Chirality and Reversible Chiroptical Switching in New Chiral Liquid‐Crystal Azopolymers

Deformation of amorphous azobenzene-containing polymer films induced by polarized light

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