The chemical structures of Co oxynitrides – in particular, interactions among N and O atoms bonded to the same cobalt – are of great importance for an array of catalytic and materials applications. X-ray diffraction (XRD), core and valence band X-ray photoelectron spectroscopy (XPS) and plane wave density functional theory (DFT) calculations are used to probe chemical and electronic interactions of nitrogen-rich CoO1-xNx (x > 0.7) films deposited on Si(100) using NH3 or N2 plasma-based sputter deposition or surface nitridation. Total energy calculations indicate that the zincblende (ZB) structure is energetically favored over the rocksalt (RS) structure for x > ~ 0.2, with an energy minimum observed in the ZB structure for x ~ 0.8 - 0.9. This is in close agreement with XPS-derived film compositions when corrected for surface oxide/hydroxide layers. XRD data indicate that films deposited on Si (100) at room temperature display either a preferred (220) orientation or no diffraction pattern, and are consistent with either rocksalt (RS) or zincblende (ZB) structure. Comparison between experimental and calculated X-ray excited valence band densities of states – also similar for all films synthesized herein – demonstrates a close agreement with a ZB, but not an RS structure. Core levelmore »
The price of schedulability in cyclic workloads: The history-vs.-response-time-vs.-accuracy trade-off
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Analyzing a list of all Small Business Administration (SBA) loans in 1991 to 2009 linked with annual information on all U.S. employers from 1976 to 2012, we apply detailed matching and regression methods to estimate the variation in SBA loan effects on job creation and firm survival across firm age and size groups. The number of jobs created per million dollars of loans generally increases with size and decreases in age. The results imply that fast-growing firms (“gazelles”) experience the greatest financial constraints to growth, while the growth of small, mature firms is least financially constrained. The estimated association between survival and loan amount is larger for younger and smaller firms facing the “valley of death”.