<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Positron annihilation studies of liquid crystals are reviewed with particular reference to thermotropic liquid crystals with rod-like molecules. The studies of compounds exhibiting smectic A or smectic E phases indicate that local arrangement of dipole molecules play an important role because high electron density at the end group of molecules can influence substantially formation and annihilation of positronium. The obtained <italic>ortho</italic>-positronium lifetimes in these phases can be explained by antiparallel pairing of molecules in case of the smectic A phase or a structure with a nanosegregation of alkyl chains and others parts of molecules into sublayers and liquid-like state of alkyl chains in case of the smectic E phase.</p></abstract>

Positron annihilation studies of liquid crystals are reviewed with particular reference to thermotropic liquid crystals with rod-like molecules. The studies of compounds exhibiting smectic A or smectic E phases indicate that local arrangement of dipole molecules play an important role because high electron density at the end group of molecules can influence substantially formation and annihilation of positronium. The obtained ortho-positronium lifetimes in these phases can be explained by antiparallel pairing of molecules in case of the smectic A phase or a structure with a nanosegregation of alkyl chains and others parts of molecules into sublayers and liquid-like state of alkyl chains in case of the smectic E phase.

Positron annihilation in liquid crystals

Institute of Nuclear Physics of the Polish Academy of Sciences, 152 Radzikowskiego Str., 31-342 Kraków, Poland, Tel.: +48 12 662 8370, Fax: +48 12 662 8458

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{"article-title":"Positron annihilation in liquid crystals"}

Positron annihilation studies of liquid crystals are reviewed with particular reference to thermotropic liquid crystals with rod-like molecules. The studies of...

Positron annihilation in liquid crystals

Published Online: Dec 01, 2015

Page range: 703 - 708

Received: Jun 25, 2015

Accepted: Aug 25, 2015

DOI: https://doi.org/10.1515/nuka-2015-0125

Keywords
liquid crystals, positron annihilation, phase transitions

© 2015 Ewa Dryzek et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Positron annihilation in liquid crystals

Published Online: Dec 01, 2015

Page range: 703 - 708

Received: Jun 25, 2015

Accepted: Aug 25, 2015

DOI: https://doi.org/10.1515/nuka-2015-0125

Keywordsliquid crystals, positron annihilation, phase transitions

© 2015 Ewa Dryzek et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
liquid crystals, positron annihilation, phase transitions