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Chirality effects on 2D phase transitions
journal contribution
posted on 2023-06-08, 18:28 authored by Enrico Scalas, G Brezesinski, H Möhwald, V M Kaganer, W G Bouwman, K KjaerMonolayers 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.
History
Publication status
- Published
Journal
Thin Solid FilmsISSN
0040-6090Publisher
ElsevierExternal DOI
Volume
284-5Page range
56-61Department affiliated with
- Mathematics Publications
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- No
Peer reviewed?
- Yes
Legacy Posted Date
2014-10-03Usage metrics
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