2,110 research outputs found
Surface effects on the Mott-Hubbard transition in archetypal VO
We present an experimental and theoretical study exploring surface effects on
the evolution of the metal-insulator transition in the model Mott-Hubbard
compound Cr-doped VO. We find a microscopic domain formation that is
clearly affected by the surface crystallographic orientation. Using scanning
photoelectron microscopy and X-ray diffraction, we find that surface defects
act as nucleation centers for the formation of domains at the
temperature-induced isostructural transition and favor the formation of
microscopic metallic regions. A density functional theory plus dynamical mean
field theory study of different surface terminations shows that the surface
reconstruction with excess vanadyl cations leads to doped, and hence more
metallic surface states, explaining our experimental observations.Comment: 5 pages, 4 figure
Irradiation-energy Dependence on the Spectral Changes of Hydrous C-Type Asteroids Based on 4kev and 20kev He Exposure Experiments of Murchison Cm Chondrite
C-type asteroid 162173 Ryugu was observed by remote sensing apparatus onboard Hayabusa2 spacecraft and found to be very dark object whose reflectance is (1.60 0.15) % at 0.55m and showed a small 2.7m absorption band indicative of phyllosilicates. The optical navigation camera detected color variations of Ryugus surface in the wavelength range from 0.4 to 0.95m: Bluer spectra are ob-served at both poles and on the equatorial ridge, both of which are topographic highs and thus may be fresh material exposed by gradual erosion. On the other hand, many locations at middle-latitude areas exhibit redder and darker colors. Similar color variations are also detected in the near-infrared wavelength range. These observations suggest that a surface-correlated process is responsible for the color variation, most prob-ably from blue to red, but the mechanism for the change is not yet identified. Space weathering is one possible mechanism responsible for the color variation, but the spectral changes of C-type asteroids from space weathering are far from being fully understood. Past experimental studies using hydrous carbonaceous chondrites such as Murchison and Tagish Lake show that He exposure (simulating solar wind irradiation) changes spectra to bluer and brighter. Recently our He exposure experiments indicate that spectral changes depend on physical properties such as porosity of exposed material. In this study, we per-formed further He exposure experiments using Murchison CM chondrite in order to understand energy dependence on the spectral changes. We found that He energy is a critical parameter, as well as physical properties of the samples, that affects spectral changes of space weathering of hydrated C-type asteroids
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Attitudes of U.S. Wind Turbine Neighbors: Analysis of a Nationwide Survey
Experts predict continuing deployment of wind turbines in the United States, which will create more interactions between turbines and surrounding communities. Policymakers can benefit from analyses of existing wind projects that enable them to better understand likely effects on residents around proposed projects. Our analysis of a randomly drawn, representative national survey of 1705 existing U.S. wind project neighbors provides previously unavailable detail about factors influencing the attitudes of these neighbors toward their local wind projects. Overall, we find positive-leaning attitudes, which improve over time as individuals self-select into communities near existing wind projects. Hearing wind turbines leads to less-positive attitudes, although living very near to turbines does not, nor does seeing wind turbines. In fact, our findings suggest complex relationships among nearby residents’ attitudes, their perceptions about the particular fit of turbines within their landscape and community, and their perceptions of wind project impacts on property values. These findings—along with the positive correlation between perceived planning-process fairness and attitude—suggest areas of focus for wind project development that may influence social outcomes and acceptance of wind energy. The concluding discussion provides a number of policy and future research recommendations based on the research
Spectroscopy of 32Ne and the Island of Inversion
We report on the first spectroscopic study of the N=22 nucleus 32Ne at the
newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line
with an energy of 722(9) keV was observed in both inelastic scattering of a 226
MeV/u 32Ne beam on a Carbon target and proton removal from 33Na at 245 MeV/u.
This transition is assigned to the de-excitation of the first J^pi = 2+ state
in 32Ne to the 0+ ground state. Interpreted through comparison with
state-of-the-art shell model calculations, the low excitation energy
demonstrates that the Island of Inversion extends to at least N=22 for the Ne
isotopes.Comment: Accepted for publication in Phys. Rev. Lett. 11 pages, 3 figure
A Cryogenic Silicon Interferometer for Gravitational-wave Detection
The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of the existing LIGO observatory facilities, we have designed a new instrument that will have 5 times the range of Advanced LIGO, or greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor
Search for Gravitational Wave Bursts from Soft Gamma Repeaters
We present the results of a LIGO search for short-duration gravitational
waves (GWs) associated with Soft Gamma Repeater (SGR) bursts. This is the first
search sensitive to neutron star f-modes, usually considered the most efficient
GW emitting modes. We find no evidence of GWs associated with any SGR burst in
a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190
lesser events from SGR 1806-20 and SGR 1900+14 which occurred during the first
year of LIGO's fifth science run. GW strain upper limits and model-dependent GW
emission energy upper limits are estimated for individual bursts using a
variety of simulated waveforms. The unprecedented sensitivity of the detectors
allows us to set the most stringent limits on transient GW amplitudes published
to date. We find upper limit estimates on the model-dependent isotropic GW
emission energies (at a nominal distance of 10 kpc) between 3x10^45 and 9x10^52
erg depending on waveform type, detector antenna factors and noise
characteristics at the time of the burst. These upper limits are within the
theoretically predicted range of some SGR models.Comment: 6 pages, 1 Postscript figur
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