Encapsulation kinetics and dynamics of carbon monoxide in clathrate hydrate.

Carbon monoxide clathrate hydrate is a potentially important constituent in the solar system. In contrast to the well-established relation between the size of gaseous molecule and hydrate structure, previous work showed that carbon monoxide molecules preferentially form structure-I rather than structure-II gas hydrate. Resolving this discrepancy is fundamentally important to understanding clathrate formation, structure stabilization and the role the dipole moment/molecular polarizability plays in these processes. Here we report the synthesis of structure-II carbon monoxide hydrate under moderate high-pressure/low-temperature conditions. We demonstrate that the relative stability between structure-I and structure-II hydrates is primarily determined by kinetically controlled cage filling and associated binding energies. Within hexakaidecahedral cage, molecular dynamic simulations of density distributions reveal eight low-energy wells forming a cubic geometry in favour of the occupancy of carbon monoxide molecules, suggesting that the carbon monoxide-water and carbon monoxide-carbon monoxide interactions with adjacent cages provide a significant source of stability for the structure-II clathrate framework

Stroboscopic Time-of-Flight Neutron Diffraction in Long Pulsed Magnetic Fields

We present proof-of-principle experiments of stroboscopic time-of-flight (TOF) neutron diffraction in long pulsed magnetic fields. By utilizing electric double-layer capacitors, we developed a long pulsed magnet for neutron diffraction measurements, which generates pulsed magnetic fields with the full widths at the half maximum of more than $10^2$ ms. The field variation is slow enough to be approximated as a steady field within the time scale of a polychromatic neutron pulse passing through a sample placed in a distance of the order of $10^1$ m from the neutron source. This enables us to efficiently explore the reciprocal space using a wide range of neutron wavelength in high magnetic fields. We applied this technique to investigate field-induced magnetic phases in the triangular lattice antiferromagnets CuFe$_{1-x}$Ga$_x$O$_2$ ($x=0, 0.035$).Comment: 9 pages, 7 figure

Highly asymmetric lamellar nanostructures from nanoparticle-linear hybrid block copolymers

The highly asymmetric lamellar (A-LAM) nanostructure is one of the most important template geometries for block copolymer (BCP) lithography. However, A-LAM is unattainable from conventional BCPs, and there is no general molecular design strategy for A-LAM-forming BCP. Herein, a nanoparticle-linear hybrid BCP system is reported, which is designed based on the intramolecular crosslinking technique, as a remarkably effective platform to obtain the A-LAM morphology. The hybrid BCPs consisting of polystyrene single-chain nanoparticles and linear polylactide segments show a remarkable capability to form the A-LAM morphology in bulk, where a maximum width ratio of 4.1 between the two domains is obtained. This unusual phase behavior is attributed to the bulky and rigid characteristics of the nanoparticle block. Furthermore, the thin films of these hybrid BCPs show perpendicularly oriented A-LAM morphology on a chemically modified Si substrate, allowing promising application in the fabrication of asymmetric line-and-space nanopatterns