Eur. Phys. J. E (2007) 23: 281-287
https://doi.org/10.1140/epje/i2007-10189-0

Regular Article

Deduction of the temperature-dependent structure of the four-layer intermediate smectic phase using resonant X-ray scattering

¹ School of Physics and Astronomy, University of Manchester, M13 1PL, Manchester, UK
² School of Physics and Astronomy, University of Minnesota, 55455, Minneapolis, MN, USA
³ Brookhaven National Laboratory, NSLS, 11973, Upton, NY, USA

^* e-mail: helen.gleeson@manchester.ac.uk

Received: 23 April 2007
Accepted: 7 June 2007
Published online: 20 July 2007

Abstract

A binary mixture of an antiferroelectric liquid-crystal material containing a selenium atom and a highly chiral dopant is investigated using resonant X-ray scattering. This mixture exhibits a remarkably wide four-layer intermediate smectic phase, the structure of which is investigated over a temperature range of 16K. Analysis of the resonant X-ray scattering data allows accurate measurement of both the helicoidal pitch and the distortion angle as a function of temperature. The former decreases rapidly as the SmC ^* phase is approached, whilst the latter remains constant over the temperature range studied at 8^°±3^° . We also observe that the senses of the helicoidal pitch and the unit cell of the repeating four-layer structure are opposite in this mixture and that there is no pitch inversion over the temperature range studied.