9,448 research outputs found

    Electron paramagnetic resonance and photochromism of N3V0\mathrm{N}_{3}\mathrm{V}^{0} in diamond

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    The defect in diamond formed by a vacancy surrounded by three nearest-neighbor nitrogen atoms and one carbon atom, N3V\mathrm{N}_{3}\mathrm{V}, is found in 98%\approx98\% of natural diamonds. Despite N3V0\mathrm{N}_{3}\mathrm{V}^{0} being the earliest electron paramagnetic resonance spectrum observed in diamond, to date no satisfactory simulation of the spectrum for an arbitrary magnetic field direction has been produced due to its complexity. In this work, N3V0\mathrm{N}_{3}\mathrm{V}^{0} is identified in 15N^{15}\mathrm{N}-doped synthetic diamond following irradiation and annealing. The 15N3V0\mathrm{^{15}N}_{3}\mathrm{V}^{0} spin Hamiltonian parameters are revised and used to refine the parameters for 14N3V0\mathrm{^{14}N}_{3}\mathrm{V}^{0}, enabling the latter to be accurately simulated and fitted for an arbitrary magnetic field direction. Study of 15N3V0\mathrm{^{15}N}_{3}\mathrm{V}^{0} under excitation with green light indicates charge transfer between N3V\mathrm{N}_{3}\mathrm{V} and Ns\mathrm{N_s}. It is argued that this charge transfer is facilitated by direct ionization of N3V\mathrm{N}_{3}\mathrm{V}^{-}, an as-yet unobserved charge state of N3V\mathrm{N}_{3}\mathrm{V}

    Generalized Mean Field Approach to a Resonant Bose-Fermi Mixture

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    We formulate a generalized mean-field theory of a mixture of fermionic and bosonic atoms, in which the fermion-boson interaction can be controlled by a Feshbach resonance. The theory correctly accounts for molecular binding energies of the molecules in the two-body limit, in contrast to the most straightforward mean-field theory. Using this theory, we discuss the equilibrium properties of fermionic molecules created from atom pairs in the gas. We also address the formation of molecules when the magnetic field is ramped across the resonance, and present a simple Landau-Zener result for this process.Comment: 35 page

    A New Study of the Transition to Uniform Nuclear Matter in Neutron Stars and Supernovae

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    A comprehensive microscopic study of the properties of bulk matter at densities just below nuclear saturation ρs=2.51014\rho_s = 2.5 \sim 10^{14} g cm3^{-3}, zero and finite temperature and high neutron fraction, is outlined, and preliminary results presented. Such matter is expected to exist in the inner crust of neutron stars and during the core collapse of massive stars with $M \gtrsim 8M_{\odot}Comment: 4 pages, 2 figures. Participant Contribution at the ``Dense Matter in Heavy Ion Collisions and Astrophysics" Summer School, JINR, Dubna, Aug. 21 - Sept. 1, 2006. To be published in PEPAN letter

    The Response to a Perturbation in the Reflection Amplitude

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    We apply inverse scattering theory to calculate the functional derivative of the potential V(x)V(x) and wave function ψ(x,k)\psi(x,k) of a one-dimensional Schr\"odinger operator with respect to the reflection amplitude r(k)r(k).Comment: 16 pages, no figure
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