Interlayer structures of the chiral smectic liquid crystal phases revealed by resonant x-ray scattering

Hirst, Linda S.; Watson, Sandra; Gleeson, Helen F.; Cluzeau, P.; Barois, P.; Pindak, R.; Pitney, J. A.; Cady, A.; Johnson, Patrick; Huang, C. C.; Levelut, A. M.; Srajer, G.; Pollmann, J.; Seed, Alexander J.; Herbert, Mark R.; Goodby, John W.; Hird, Michael

doi:10.1103/physreve.65.041705

Cited by 100 publications

(69 citation statements)

References 29 publications

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“…Another interesting example was found in chiral smectic liquid crystals with an incommensurate spiral structure (Mach et al, 1998;Levelut & Pansu, 1999;Gorkunov et al, 1999;Matkin et al, 2000;Hirst et al, 2002); the issue was recently surveyed by Clegg (2005). The observations of 'forbidden' reflections near the S and Se K edges provided the first direct evidence of distinct periodicities in the structures of several chiral smectic phases.…”

Section: Acta Cryst (2005) A61 481-493mentioning

confidence: 98%

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

et al. 2005

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Symmetry and physical aspects of 'forbidden' reflections excited by a local polarization anisotropy of the X-ray susceptibility are surveyed. Such reflections are observed near absorption edges where the anisotropy is caused by distortions of the atomic electronic states owing to interaction with neighbouring atoms. As a consequence, they allow for extracting nontrivial information about the resonant atom's local environment and their physical conditions. The unusual polarization properties of the considered reflections are helpful to distinguish them from other types of 'forbidden' reflections. When such reflections are excited, it is, for example, possible to determine not only the intrinsic anisotropy of an atomic form factor but also additional anisotropy induced by thermal motion, point defects and/or incommensurate modulations. Even the local 'chirality' of atoms in centrosymmetric crystals is accessible. Unsolved key problems and possible future developments are addressed.

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Section: Acta Cryst (2005) A61 481-493mentioning

confidence: 98%

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

et al. 2005

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“…This intriguing similarity was investigated in reference [18]. It was found that a continuous transition can occur between the two phases, hence confirming the equivalence of their symmetries.…”

Section: Interpretation Of Datamentioning

confidence: 55%

Application of X-ray resonant diffraction to structural studies of liquid crystals

Barois

Gleeson

Huang

et al. 2012

Eur. Phys. J. Spec. Top.

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Abstract. Liquid crystals are soft materials that combine the fluidity of disordered liquids and the long range orientational or positional order of crystalline solids along one or two directions of space. X-ray scattering is widely and generally successfully used to investigate and characterize the microscopic structure of most liquid crystals. In many cases however, the Bragg reflections are forbidden by special symmetries of the unit cell and the low dimensional structure of the liquid crystalline phases are out of reach of conventional X-ray experiments. We show in this paper that this problem can be overcome by resonant scattering of X-rays as it reveals the anisotropy of the tensor structure factor. We review various examples in which the restored forbidden reflections reveal unambiguously the hidden structure of liquid crystalline phases. Moreover, we show that in some cases, a fine analysis of the polarization of the Bragg reflections enables one to discriminate between different structural models. These studies solved long standing questions about biaxial liquid crystal structures and provided new insights into physical phenomena such as supercritical behaviour or commensurate-incommensurate transitions.

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“…One example is provided by the work of Tanaka et al [36] who have shown that the use of circular polarisation can reveal handedness of crystals. More generally, such methods could be applied to a wide range of chiral motifs such as liquid crystals [37] or ferroelectrics and multiferroics [38].…”

Section: Deciphering Local Site Symmetry Propertiesmentioning

confidence: 99%

Resonant elastic X-ray scattering: Where from? where to?

Vettier

2012

Eur. Phys. J. Spec. Top.

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Abstract. The International Conference on Anomalous Scattering held in Malente, Germany, in 1992 examined the broad issue of 'dispersion or resonant scattering' for X-rays. The significant aspects discussed at that time included: the evaluation of X-ray scattering factors, the role of local broken symmetries and the application to structure determinations, the impact on magnetic X-ray scattering, but also resonant Raman scattering and nuclear resonant scattering. However, many aspects of resonant elastic X-ray scattering (REXS) were still being revealed and soon it was realised that new productive paths of research would open up. In the last two decades, applications have developed thanks to concurrent developments in X-ray instrumentation and theoretical approaches. Focusing on REXS only, noteworthy fields are: the observation of multiple order parameters, the detection of multipolar moments, but also applications in chemistry and materials sciences, macromolecules and soft matter in the soft X-ray range. REXS has evolved from the exploitation of large resonant signals to a powerful experimental and characterisation method aimed at unravelling new phenomena. The recent technical and theoretical advances have paved the way to further REXS developments in many fields of science.

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Interlayer structures of the chiral smectic liquid crystal phases revealed by resonant x-ray scattering

Cited by 100 publications

References 29 publications

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

Application of X-ray resonant diffraction to structural studies of liquid crystals

Resonant elastic X-ray scattering: Where from? where to?

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