Structures of chiral smectic-C mesophases revealed by polarization-analyzed resonant x-ray scattering.
We report polarization-analyzed, resonant x-ray diffraction at the sulfur K edge performed upon free-standing liquid-crystal films. Our studies of the thiobenzoate liquid-crystal enantiomer 10OTBBB1M7 yield the polarization states of resonant satellite peaks arising from characteristic superlattices in the chiral smectic-C (SmC(*)) variant phases, including the antiferroelectric SmC(*)(A), ferrielectric SmC(*)(FI1) and SmC(*)(FI2), as well as SmC(*)(alpha). The observed polarizations agree with the clock model of chiral smectic-C variants, and rule out other proposals made to date for these structures. Data from the 10OTBBB1M7 racemate also support the clock model. Our resonant diffraction results from a thiophene liquid-crystal compound reveal the same superlattice periodicities seen in corresponding antiferroelectric and ferrielectric phases of 10OTBBB1M7.
Mach
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P
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Pindak
R
R
Levelut
A M
AM
Barois
P
P
Nguyen
H T
HT
Baltes
H
H
Hird
M
M
Toyne
K
K
Seed
A
A
Goodby
J W
JW
Huang
C C
CC
Furenlid
L
L