Publications

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We will present our experiences with the new High Energy Resolution Optics (HERO) upgrade on a Physical Electronics Auger 690 system. This upgrade allows the single pass cylindrical analyzer in the Auger system to achieve higher energy resolution than in the standard mode. With this upgrade, it should be possible to separate chemical states for certain elements. Also, it should be possible to separate closely spaced peaks from selected elements that have been difficult or impossible to separate without the upgrade. Specifically, we will investigate practical use of this upgrade in the analysis of materials systems where overlapping peaks have historically been an issue, such as Kovar, which consists of the elements Ni, Fe and Co. Strategies for the successful use of the technique as well as its current limitations will be shown.

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Erbium is known to effectively load with hydrogen when held at high temperature in a hydrogen atmosphere. To make the storage of hydrogen kinetically feasible, a thermal activation step is required. Activation is a routine practice, but very little is known about the physical, chemical, and/or electronic processes that occur during Activation. This work presents in situ characterization of erbium Activation using variable energy photoelectron spectroscopy at various stages of the Activation process. Modification of the passive surface oxide plays a significant role in Activation. The chemical and electronic changes observed from core-level and valence band spectra will be discussed along with corroborating ion scattering spectroscopy measurements.

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In an aim to develop photo-responsive composites, the UV photo-reduction of aqueous titanium oxide nanoparticle-graphene oxide (TiO{sub 2}-GO) dispersions (Lambert et al. J Phys. Chem. 2010 113 (46), 19812-19823) was undertaken. Photo-reduction led to the formation of a black precipitate as well as a soluble portion, comprised of titanium oxide nanoparticle-reduced graphene oxide (TiO{sub 2}-RGO). When allowed to slowly evaporate, self assembled titanium oxide nanoparticle-graphene oxide (SA-TiO{sub 2}-RGO) films formed at the air-liquid interface of the solution. The thickness of SARGO-TiO{sub 2} films range from {approx}30-100 nm when deposited on substrates, and appear to be comprised of a mosaic assembly of graphene nanosheets and TiO{sub 2}, as observed by scanning electron microscopy. Raman spectroscopy and X-ray photoelectron spectroscopy indicate that the graphene oxide is only partially reduced in the SA-TiO{sub 2}-RGO material. These films were also deposited onto inter-digitated electrodes and their photo-responsive behavior was examined. UV-exposure lead to a {approx} 200 kOhm decrease in resistance across the device, resulting in a cathodically biased film. The cathodic bias of the films was utilized for the subsequent reduction of Ag(NO{sub 3}) into silver (Ag) nanoparticles, forming a ternary Ag-(SA-RGO-TiO{sub 2}) composite. Various aspects of the self assembled films, their photoconductive properties as well as potential applications will be presented.

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