The SmA phase of a bent-core V-shaped compound: structure and electric-field response

Abstract

The smectic A (SmA) phase of a V-shaped mesogen with a molecular bending angle of 60° was studied. According to X-ray measurements, the molecules are arranged with the ‘bow-string’ direction parallel to the smectic layer. This point was confirmed by birefringence analysis and the result is compatible with a non-polar structure. A detailed study of the (001) smectic layer reflection versus temperature was also carried out to determine the smectic translational order parameter. The results indicate that the material presents a high degree of translational order. In addition, the electric field response of the material was studied by means of second harmonic generation. This technique turned out to be highly sensitive to small structural distortions due to the V-shape of the constituent molecules.

Keywords:

• V-shaped molecule
• second harmonic generation
• X-ray
• phase transition

Acknowledgements

This research was supported by CICYT-FEDER of Spain-UE MAT2008-06522-CO2 and MAT2009-14636-CO3, the Aragón Government (E04), and the Basque Country Government (Project No. GIC-10/45). N.G. acknowledges the Spanish Government for a Juan de la Cierva fellowship.