Distribution and Mobility of Amines Confined in Porous Silica Supports Assessed via Neutron Scattering, NMR, and MD Simulations: Impacts on CO Sorption Kinetics and Capacities.

ConspectusSolid-supported amines are a promising class of CO sorbents capable of selectively capturing CO from diverse sources. The chemical interactions between the amine groups and CO give rise to the formation of strong CO adducts, such as alkylammonium carbamates, carbamic acids, and bicarbonates, which enable CO capture even at low driving force, such as with ultradilute CO streams. Among various solid-supported amine sorbents, oligomeric amines infused into oxide solid supports (noncovalently supported) are widely studied due to their ease of synthesis and low cost.

Irradiation stability and induced ferromagnetism in a nanocrystalline CoCrCuFeNi highly-concentrated alloy.

In the field of radiation damage of crystalline solids, new highly-concentrated alloys (HCAs) are now considered to be suitable candidate materials for next generation fission/fusion reactors due to recently recorded outstanding radiation tolerance. Despite the preliminarily reported extraordinary properties, the mechanisms of degradation, phase instabilities and decomposition of HCAs are still largely unexplored fields of research. Herein, we investigate the response of a nanocrystalline CoCrCuFeNi HCA to thermal annealing and heavy ion irradiation in the temperature range from 293 to 773 K with the objective to analyze the stability of the nanocrystalline HCA in extreme conditions.

Electron-Beam-Induced Molecular Plasmon Excitation and Energy Transfer in Silver Molecular Nanowires.

We investigate (1) electron-beam-induced plasmon absorption spectra of Ag molecular nanowire dimers and (2) electron-beam-induced energy transfer between two nanowires. We employ linear-response time-dependent density functional theory (TDDFT) and real-time TDDFT methods to simulate the electron-beam-induced plasmonic excitations, dynamics, and corresponding electron energy loss spectrum for small models of a single molecular nanowire with four Ag atoms and for two Ag nanowires. An array of different relative orientations of nanowires and of different initial excitation conditions resulting from applying an electron beam at different positions with respect to the Ag nanowires is investigated.

A fast scheme to calculate electronic couplings between P3HT polymer units using diabatic orbitals for charge transfer dynamics simulations.

We propose a fast and accurate calculation method to compute the electronic couplings between molecular units in a thiophene-ring-based polymer chain mimicking a real organic semiconducting polymer, poly(3-hexylthiophene). Through a unit block diabatization scheme, the method employed minimal number of diabatic orbitals to compute the site energies and electronic couplings, which were validated by comparing with benchmark density functional theory calculations. In addition, by using the obtained electronic couplings, a quantum dynamics simulation was carried out to propagate a hole initially localized in a thiophene-ring unit of the polymer chain.

Centrifugal-driven, reduced-dimension, planar chromatography.

A fundamental problem with efficiency in capillary action driven planar chromatography results from diminishing flow rates as development proceeds, giving rise to molecular diffusion related band dispersion for most sample types. Overpressure and electrokinetic means to speed flow have been used successfully in TLC. We explore the use of centrifugal force (CF) to drive flow for reduced-dimension planar platforms (ultra-TLC, low micrometer features, and nano-TLC, nanoscale features).

Achieving atomic resolution magnetic dichroism by controlling the phase symmetry of an electron probe.

The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration-corrected optics of a scanning transmission electron microscope. The required phase distribution of the probe depends on the magnetic symmetry and crystal structure of the sample.

Disk-cylinder and disk-sphere nanoparticles via a block copolymer blend solution construction.

Researchers strive to produce nanoparticles with complexity in composition and structure. Although traditional spherical, cylindrical and membranous, or planar, nanostructures are ubiquitous, scientists seek more complicated geometries for potential functionality. Here we report the simple solution construction of multigeometry nanoparticles, disk-sphere and disk-cylinder, through a straightforward, molecular-level, blending strategy with binary mixtures of block copolymers.