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A photoemission electron microscope (PEEM) was recently commissioned at the NIST. To benchmark its capabilities, epitaxial graphene on 4H-SiC (0001) was imaged and analyzed in the PEEM and compared to other complementary imaging techniques. We determine our routine spatial resolution to be about 50 nm. Using the well-known electronic structure of graphene as a reference, we outline a procedure to calibrate our instrument in energy and momenta in the micrometer-angle-resolved photoemission spectroscopy (μ-ARPES). We also determine the energy and momenta resolution to be about 300 meV, 0.08 Å−1 (ky), and 0.2 Å−1 (kx), respectively. We identify distinct regions of the graphene surface based on intensity contrast rising from topographic and electronic contrasts as well as μ-ARPES. These regions are one layer graphene, one SiC buffer layer, and ≥2 layers of graphene (or graphite). These assignments are confirmed using confocal laser scanning microscopy and Raman spectroscopy. Finally, the PEEM instrument had enough sensitivity to observe the flatband in monolayer epitaxial graphene, which we attribute to the presence of compressive strain, −1.2%, in the graphene sample. [ABSTRACT FROM AUTHOR]

The metallization of CoSi2 thin films on GaAs reveals several new features of the CoSi2 films. The annealing process occurring below a temperature of 700 degrees Celsius does not result in the stimulation of any reaction between the GaAs and CoSi2 overlayers. The GaAs/CoSi2 interface is found to be sharp and the grain growth increases with increase in the annealing temperature. The excess surface Si near the interface does not migrate into the GaAs surface.

Resist residue from the device fabrication process is a significant source of contamination at the metal/graphene contact interface. Ultraviolet Ozone (UVO) treatment is proven here, by X-ray photoelectron spectroscopy and Raman measurement, to be an effective way of cleaning the metal/graphene interface. Electrical measurements of devices that were fabricated by using UVO treatment of the metal/graphene contact region show that stable and reproducible low resistance metal/graphene contacts are obtained and the electrical properties of the graphene channel remain unaffected. [ABSTRACT FROM AUTHOR]

This work describes the design and validation of an instrument to measure the kinetic energies of ions ejected by the pulsed laser ablation (PLA) of a solid target. Mass spectra show that the PLA of Ni, Al, and ZnO targets, in vacuum, using the second harmonic of a Nd:YAG laser (532 nm, pulse duration ∼10 ns) generates abundant Xn+ ions (n≤3 for Ni, ≤2 for Al, ≤3 and ≤2 for Zn and O respectively from ZnO). Ions are selected by their mass/charge (m/z) ratio prior to the determination of their times of flight. PLA of Ni has been studied in most detail. The mean velocities of ablated Nin+ ions are shown to follow the trend v(Ni3+)>v(Ni2+)>v(Ni+). Data from Ni2+ and Ni3+ are fitted to shifted Maxwellian functions and agree well with a model which assumes both thermal and Coulombic contributions to ion velocities. The dependence of ion velocities on laser pulse energy (and fluence) is investigated, and the high energy data are shown to be consistent with an effective accelerating voltage of ∼90 V within the plume. The distribution of velocities associated with Ni3+ indicates a population at cooler temperature than Ni2+. [ABSTRACT FROM AUTHOR]

Ordered Au nanodisk arrays were fabricated on glass substrates using nanosphere lithography combined with a two-step reactive ion etching technique. The optical properties of these arrays were investigated both experimentally and theoretically. Specifically, the effects of disk diameter on localized surface plasmon resonance (LSPR) were characterized and compared with results from discrete dipole approximation (DDA) calculations. The effects of glass substrate, Cr interfacial layer, and Au thickness on LSPR were investigated computationally. Furthermore, thermal treatment was found to be essential in improving the nanodisk arrays’ LSPR properties. Using atomic force microscopy and DDA calculations, it was established that the improvements in LSPR properties were due to thermally induced morphologic changes. Finally, microfluidic channels were integrated with the annealed disk arrays to study the sensitivity of LSPR to the change in surroundings’ refractive index. The dependence of LSPR on surroundings’ refractive index was measured and compared with calculated results. [ABSTRACT FROM AUTHOR]

Ordered Au nanodisk arrays are fabricated on glass substrates by using nanosphere lithography combined with a two-step reactive ion etching method. The dependence of localized surface plasmon resonance (LSPR) on surroundings' refractive index is measured and compared to discrete dipole approximation (DDA)-calculated results.

Explores the electrode erosion mechanisms in high-power vortex stabilized arc lamps. Factors important to the removal of electrode material; Method used to test the effect of thermal loading on the electrode erosion rate; Investigation on the possibility of reducing the anode heat flux with an applied magnetic field.

Reports on the measurement of the ac response of two thin-film magnetic recording heads placed in mirror symmetry with respect to one another. Area of the coils and the pole tips; Apparatus used to investigate the heads; Information on the response of pairs of Cybernex heads; Method used to obtain information about the absolute response of the head.

Presents a study which calculated the magnetic energy of imperfect films having a two-dimensional square-lattice structure with voids between square islands of magnetic material for arbitrary ration of thickness and island size to the period of the lattice. Relevance of the calculations; Directional dependence of the magnetization energy; Conclusion.

Presents information on a study that investigated the rotational hysteresis of zero-field samples in the compositional series copper[sub1-x]manganese[sub0.15]gold[subx]. Experimental procedures; Results and discussion; Conclusion.

Presents a study which performed longitudinal magneto-optical Kerr effect measurements on bilayers consisting of a thick permalloy film covered by varying thicknesses of niobium. Experimental procedures; Results and discussion; Conclusion.