Chirality effects on 2D phase transitions

Scalas, E, Brezesinski, G, Möhwald, H, Kaganer, V M, Bouwman, W G and Kjaer, K (1996) Chirality effects on 2D phase transitions. Thin Solid Films, 284-5. pp. 56-61. ISSN 0040-6090

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Monolayers of the racemate and pure enantiomers of 1-hexadecyl-glycerol were investigated by grazing incidence X-ray diffraction (GID) at 5 and 20 °C on compression from 0 mN m−1 to pressures greater than 30 mN m−1. The racemate lattice is centred-rectangular for both temperatures at all investigated pressures. However, at both temperatures, there is a sharp phase transition from a low-pressure phase, in which the molecules are tilted towards nearest neighbours (NN) and the distortion azimuth also points towards NN, to a high-pressure phase, in which the molecules are tilted towards next-nearest neighbours (NNN) and an NNN-distorted lattice is observed. At 5 °C, the transition pressure is 15 mN m−1, whereas at 20 °C it is 18 mN m−1. Chirality destroys this transition: the pure enantiomer always exhibits an oblique lattice with tilted molecules, and the azimuths of tilt and distortion continuously vary from a direction close to NN to a direction close to NNN. The nature of the phase transition and the influence of chirality on it are discussed within the framework of Landau's theory of phase transitions.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Mathematics
Subjects: Q Science > QD Chemistry > QD0450 Physical and theoretical chemistry
Q Science > QD Chemistry > QD0901 Crystallography
Depositing User: Enrico Scalas
Date Deposited: 03 Oct 2014 11:51
Last Modified: 03 Oct 2014 11:51
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