https://doi.org/10.1007/s100510050956
Synchrotron X-ray study of the q-fold quasicrystalline symmetry of the Smectic C Twist Grain Boundary phase (TGBc)
1
Centre de Recherche Paul Pascal, CNRS,
avenue A. Schweitzer, 33600 Pessac, France
2
E.S.R.F, B.P. 220, 38043 Grenoble, France
3
G.D.P.C. (UMR 5581 du CNRS) ,
Université Montpellier II, 34000 Montpellier, France
4
Bell Labs, Lucent Technologies, Murray Hill, NJ 07974, USA
Received:
18
January
1999
Published online: 15 October 1999
We report the first X-ray
scattering investigation of spatial variations of the q-fold
quasicrystalline symmetry (so-called commensurability) of
well-aligned samples. A spatial
resolution of
was achieved using the ESRF microfocus beamline. The liquid crystal
samples, contained between glass plates which were either parallel or in a wedge geometry, were
scanned in order (i) to probe the mosaicity and (ii) to continuously change the balance between
surface and volume effects. In the case of parallel plate cells, commensurability was observed
everywhere throughout the sample, hence ruling out possible
effects of mosaicity to explain the q-fold symmetry of the diffraction patterns previously reported when probed with a spatial resolution
of
mm2 in rotating anode experiments.
In the case of wedge cells, the evolution of X-ray
patterns with thickness suggested that commensurate lockin occurs for sufficiently thick samples
with a width that is statistical.
PACS: 61.30.Eb – Experimental determinations of smectic, nematic, cholesteric, and other structures / 61.10.-i – X-ray diffraction and scattering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999