1,550,772 research outputs found
Evolution of the electronic structure across the filling-control and bandwidth-control metal-insulator transitions in pyrochlore-type Ru oxides
We have performed photoemission and soft x-ray absorption studies of
pyrochlore-type Ru oxides, namely, the filling-control system
SmCaRuO and the bandwidth-control system
SmBiRuO, which show insulator-to-metal transition with
increasing Ca and Bi concentration, respectively. Core levels and the O 2
valence band in SmCaRuO show almost the same amount of
monotonous upward energy shifts with Ca concentration, which indicates that the
chemical potential is shifted downward due to hole doping. The Ru 4 band in
SmCaRuO is also shifted toward the Fermi level () with
hole doping and the density of states (DOS) at increases. The core levels
in SmBiRuO, on the other hand, do not show clear energy
shifts except for the Ru 3 core level, whose line shape change also reflects
the increase of metallic screening with Bi concentration. We observe pronounced
spectral weight transfer from the incoherent to the coherent parts of the Ru 4d
band with Bi concentration, which is expected for a bandwidth-control
Mott-Hubbard system. The increase of the DOS at is more abrupt in the
bandwidth-control SmBiRuO than in the filling-control
SmCaRuO, in accordance with a recent theoretical
prediction. Effects of charge transfer between the Bi 6 band and the Ru
4 band are also discussed.Comment: 11 pages, 6 figure
Low Mass Standard Model Higgs Limit at the Tevatron
The searches for the Standard Model (SM) Higgs Boson at the Fermilab Tevatron
by the CDF and D{\O} experiments are presented. Their state of the art
techniques, including maximizing Higgs signal acceptance, reducing background
through b-jet ID, and with Multi-Variate discrimination between signal and
background, are elucidated. The two experiments are able to achieve a
sensitivity of three to five times SM cross section ({\sigma}SM) at the
benchmark mass point of mH=115 GeV/c2 using the main search channels WH->lvbb,
ZH->vvbb, and ZH->llbb, and on combining all the channels from CDF and D{\O},
the observed (expected) limit is 1.56 (1.45) x {\sigma}SM. The present expected
limit is 1.8 x {\sigma}SM or below for the entire low mass range, and
sensitivity projections at present anticipate in Tevatron Run II a 3{\sigma}
sensitivity achievement for mH=115 GeV/c2.Comment: HCP2010 Conference Contributio
Direct evidence of soft mode behavior near the Burns' temperature in PbMgNbO (PMN) relaxor ferroectric
Inelastic neutron scattering measurements of the relaxor ferroelectric
PbMgNbO (PMN) in the temperature range
490~KT880~K directly observe the soft mode (SM) associated with the
Curie-Weiss behavior of the dielectric constant (T). The results
are treated within the framework of the coupled SM and transverse optic (TO1)
mode and the temperature dependence of the SM frequency at q=0.075 a* is
determined. The parameters of the SM are consistent with the earlier estimates
and the frequency exhibits a minimum near the Burns temperature (
650K)Comment: 6 figure
A Selective and Sensitive Chromogenic and Fluorogenic Detection of a Sulfur Mustard Simulant
A simple and highly selective chromogenic and fluorogenic detection of sulfur mustard (SM) simulants is reported. Dithiol 1, in the presence and absence of a mustard simulant behaves differently toward a squaraine dye (SQ), and thus provides a visual and spectroscopic signal for mustard gas. The sensor responds to the SM simulant, but not to the O-analog of mustard stimulant or nerve agent mimics and other electrophilic agents. The visual and fluorescent detection with less than 50 mu M of SM simulant shows good sensitivity. The utility of the sensor was demonstrated by analysis of SM simulant on surfaces, in soil, and in the gas phase.Office of Naval Research N00014-09-1-1087Welch Foundation F-1151Department of Science and Technology, IndiaDefense Research and Development Organization, IndiaChemistr
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