نتایج جستجو برای: fermi energy
تعداد نتایج: 681204 فیلتر نتایج به سال:
We consider Friedel oscillation in the two-dimensional Dirac materials when the Fermi level is near the van Hove singularity. Twisted graphene bilayer and the surface state of topological crystalline insulator are the representative materials which show low-energy saddle points that are feasible to probe by gating. We approximate the Fermi surface near saddle point with a hyperbola and calculat...
The origin, reliability and dispersion of the E p,i – E iso and other spectral energy correlations is a highly debated topic in GRB astrophysics. GRB 080916C, with its huge radiated energy (E iso ∼ 10 55 erg in the 1 keV – 10 GeV cosmological rest–frame energy band) and its intense GeV emission measured by Fermi, gives us a unique opportunity to further investigate this issue. We also include i...
Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy r...
The origin, reliability and dispersion of the E p,i – E iso and other " spectrum–energy " correlations is a highly debated topic in GRB astrophysics. GRB 080916C, with its huge radiated energy (E iso ∼ 10 55 erg in the 1 keV – 10 GeV cosmological rest–frame energy band) and its intense GeV emission measured by Fermi, gives us a unique opportunity to further investigate this issue. We also inclu...
We have studied electron transfer through redox molecules adsorbed on a conductive substrate with scanning tunneling microscopy (STM) in aqueous solution. By adjusting the substrate potential, the Fermi levels of the substrate and tip can be easily shifted relative to the energy levels of the molecules. Aligning the Fermi levels to an energy level, a nearly tenfold increase in the tunneling cur...
Thomas-Fermi theory is developed to evaluate nuclear matrix elements averaged on the energy shell, on the basis of independent particle Hamiltonians. Oneand two-body matrix elements are compared with the quantal results and it is demonstrated that the semiclassical matrix elements, as function of energy, well pass through the average of the scattered quantum values. For the one-body matrix elem...
We report ab initio calculations of quasiparticle lifetimes in graphite, as determined from the imaginary part of the self-energy operator within the GW approximation. The inverse lifetime in the energy range from 0.5 to 3.5 eV above the Fermi level presents significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the...
We have measured the heat capacity of an optically trapped, strongly interacting Fermi gas of atoms. A precise addition of energy to the gas is followed by single-parameter thermometry, which determines the empirical temperature parameter of the gas cloud. Our measurements reveal a clear transition in the heat capacity. The energy and the spatial profile of the gas are computed using a theory o...
Electron transfer from a localized state in a quantum dot into a ballistic conductor generally results in particle-hole excitations. We study this effect, considering a resonance level with time-dependent energy coupled to particle states in the Fermi sea. We find that, as the resonance level is driven through the Fermi-level, particle-hole excitations can be suppressed for certain driving prot...
We performed optical spectroscopy measurement on single crystals of BaFe2As2 and SrFe2As2, the parent compounds of FeAs-based superconductors. Both are found to be quite metallic with fairly large plasma frequencies at high temperature. Upon entering the spin-density-wave state, the formation of partial energy gaps was clearly observed with the surprising presence of two different energy scales...
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