Transverse thermal velocity broadening of focused beams from liquid metal ion sources

Experiments have shown that the target current density in focused ion beam columns have long ‘‘tails’’ outside the central submicron region. We show that these tails result from a transverse velocity distribution which has a Holtsmark probability density. Both theory and experiment show that the tails are reduced as the system magnification and source current are reduced

Hydrogen peroxide filled poly(methyl methacrylate) microcapsules: potential oxygen delivery materials

This paper describes the synthesis of H2O2–H2O filled poly(methyl methacrylate) (PMMA) microcapsules as potential candidates for controlled O2 delivery. The microcapsules are prepared by a water-in-oil solvent emulsion and evaporation method. The results of this study describe the effect of process parameters on the characteristics of the microcapsules and on their in vitro performance. The size of the microcapsules, as determined from scanning electron microscopy, ranges from ∼5 to 30 μm and the size distribution is narrow. The microcapsules exhibit an internal morphology with entrapped H2O2–H2O droplets randomly distributed in the PMMA continuous phase. In vitro release studies of 4.5 wt% H2O2-loaded microcapsules show that ∼70% of the H2O2 releases in 24 h. This corresponds to a total O2 production of ∼12 cc/gram of dry microcapsules. Shelf-life studies show that the microcapsules retain ∼84 wt% of the initially loaded H2O2 after nine months storage at 2–8 °C, which is an attractive feature for clinical applications

Oxidation chemistry of d^0 organometallic complexes

Electron-transfer processes can play an important role in organometallic chemistry. Herein, we demonstrate that even d^0 organometallic complexes exhibit a rich redox chemistry and present electrochemical, kinetics, and stereochemical studies that establish a general outer-sphere oxidation process for d^0 group 4 metallocene complexes. This oxidation chemistry closely parallels the reported LMCT photochemistry of these complexes

Two-axis control of a singlet-triplet qubit with an integrated micromagnet

The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micro magnet, the magnetic field difference $\Delta B$ between the two sides of the double dot is large enough to enable the achievement of coherent rotation of the qubit's Bloch vector about two different axes of the Bloch sphere. By measuring the decay of the quantum oscillations, the inhomogeneous spin coherence time $T_{2}^{*}$ is determined. By measuring $T_{2}^{*}$ at many different values of the exchange coupling $J$ and at two different values of $\Delta B$, we provide evidence that the micromagnet does not limit decoherence, with the dominant limits on $T_{2}^{*}$ arising from charge noise and from coupling to nuclear spins.Comment: 10 pages, 9 figure