2,305 research outputs found

    A Novel Technique for the Simultaneous Collection of Reflection and Transmission Data from Thin Films in the Extreme Ultraviolet

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    Studies of thin films in the Extreme Ultraviolet (EUV) are difficult given that most materials readily absorb photons of these energies. By depositing a thin film of the material of interest on a silicon photodiode, transmission measurements can be made throughout the EUV. If the measurements are made in a range of low absorption, the extinction coefficient, k, can be found with relative ease. However, if the materialā€™s absorption is considerable, reflection measurements are needed to supplement the transmission data in order to find the optical constants n and k. The technique developed allows for reflection and transmission measurements to be taken simultaneously, which combined, account for all of the measurable photons from the original beam: (those which cannot be counted are photons absorbed into the thin film material). Also, the technique presented allows for data to be collected from practically all angles of incidence. This technique has been applied to a thin film of scandium oxide (d=65 nm), with measurements taken over wavelengths from 2.5-25 nm, and at angles of incidence 12 degrees from grazing to normal

    Magneto-elastic coupling and competing entropy changes in substituted CoMnSi metamagnets

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    We use neutron diffraction, magnetometry and low temperature heat capacity to probe giant magneto-elastic coupling in CoMnSi-based antiferromagnets and to establish the origin of the entropy change that occurs at the metamagnetic transition in such compounds. We find a large difference between the electronic density of states of the antiferromagnetic and high magnetisation states. The magnetic field-induced entropy change is composed of this contribution and a significant counteracting lattice component, deduced from the presence of negative magnetostriction. In calculating the electronic entropy change, we note the importance of using an accurate model of the electronic density of states, which here varies rapidly close to the Fermi energy.Comment: 11 pages, 9 figures. Figures 4 and 6 were updated in v2 of this preprint. In v3, figures 1 and 2 have been updated, while Table II and the abstract have been extended. In v4, Table I has updated with relevant neutron diffraction dat

    Estimating Crime in Rural America: The Contribution of the First Phase of The West Virginia Community Quality of Life Survey

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    The study of crime, law, and social control is now much less urban-biased than it was at the start of this millennium, and there is an ongoing significant increase in international qualitative and quantitative rural criminological research. Nonetheless, a conspicuous absence of reliable estimates of crime victimization in rural parts of the United States continues to exist. This article helps fill a major research gap by presenting the results of the first phase of the West Virginia Community Quality of Life Survey

    Production of intense, coherent, tunable narrowā€band lymanā€alpha radiation

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    Nearly transform limited pulses of 1216 ƅ radiation have been generated by sum frequency generation in 0.1 to 10 torr of mercury vapor. The summed input beams, consisting of photons at 3127 ƅ and 5454 ƅ originate in 1 MHz bandā€width ringā€dye laser oscillators. The beams are amplified in pulsedā€dye amplifiers pumped by the frequency doubled output of a Nd:YAG laser. The 3127 ƅ photons are tuned to be resonant with the twoā€photon 61S to 71S mercury transition. The VUV radiation can be tuned by varying the frequency of the third nonā€resonant photon. We have also observed difference frequency generation at 2193 ƅ and intense fluorescence from the 61P state at 1849 ƅ. We have studied the intensity and linewidth dependence of the 1849 ƅ fluorescence and 1216 ƅ sum frequency signals on input beam intensity, mercury density, and buffer gas pressure and composition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87716/2/49_1.pd

    Towards improved socio-economic assessments of ocean acidificationā€™s impacts

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    Ocean acidification is increasingly recognized as a component of global change that could have a wide range of impacts on marine organisms, the ecosystems they live in, and the goods and services they provide humankind. Assessment of these potential socio-economic impacts requires integrated efforts between biologists, chemists, oceanographers, economists and social scientists. But because ocean acidification is a new research area, significant knowledge gaps are preventing economists from estimating its welfare impacts. For instance, economic data on the impact of ocean acidification on significant markets such as fisheries, aquaculture and tourism are very limited (if not non-existent), and non-market valuation studies on this topic are not yet available. Our paper summarizes the current understanding of future OA impacts and sets out what further information is required for economists to assess socio-economic impacts of ocean acidification. Our aim is to provide clear directions for multidisciplinary collaborative research

    Oceans of Impact

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