%0 Journal Article
%A Purcell, Simon
M.
%A Tesa-Serrate, Maria A.
%A Marshall, Brooks C.
%A Bruce, Duncan W.
%A D’Andrea, Lucía
%A Costen, Matthew L.
%A Slattery, John M.
%A Smoll, Eric J.
%A Minton, Timothy K.
%A McKendrick, Kenneth G.
%D 2016
%T Reactive-Atom Scattering from Liquid Crystals at the
Liquid–Vacuum Interface: [C12mim][BF4] and 4‑Cyano-4′-Octylbiphenyl (8CB)
%U https://acs.figshare.com/articles/journal_contribution/Reactive-Atom_Scattering_from_Liquid_Crystals_at_the_Liquid_Vacuum_Interface_C_sub_12_sub_mim_BF_sub_4_sub_and_4_Cyano-4_-Octylbiphenyl_8CB_/3842655
%R 10.1021/acs.langmuir.6b02440.s001
%2 https://acs.figshare.com/ndownloader/files/6008943
%K material
%K bulk order
%K OH
%K approach
%K SmA
%K transition
%K low-energy O atoms
%K cation head groups
%K CB
%K incident translational energies
%K crystal
%K mim
%K phase
%K surface structure
%X Two complementary
approaches were used to study the liquid–vacuum
interface of the liquid-crystalline ionic liquid 1-dodecyl-3-methylimidazolium
tetrafluoroborate ([C12mim][BF4]) in the smectic
A (SmA) and isotropic phases. O atoms with two distinct incident translational
energies were scattered from the surface of [C12mim][BF4]. Angle-dependent time-of-flight distributions and OH yields,
respectively, were recorded from high- and low-energy O atoms. There
were no significant changes in the measurements using either approach,
nor the properties derived from them, accompanying the transition
from the SmA to the isotropic phase. This indicates that the surface
structure of [C12mim][BF4] remains essentially
unchanged across the phase boundary, implying that the bulk order
and surface structure are not strongly correlated for this material.
This effect is ascribed to the strong propensity for the outer surfaces
of ionic liquids to be dominated by alkyl chains, over an underlying
layer rich in anions and cation head groups, whether or not the bulk
material is a liquid crystal. In a comparative study, the OH yield
from the surface of the liquid crystal, 8CB, was found to be affected
by the bulk order, showing a surprising step increase at the SmA–nematic
transition temperature, whose origin is the subject of speculation.
%I ACS Publications