347 research outputs found
Optimum Arrangement of Resonator in Micro-bunch Free Electron Laser(III. Accelerator, Synchrotron Radiation, and Instrumentation)
Using a short-bunched beam of electrons from a linear accelator, the output of the micro-bunch FEL has been studied experimentally to clarify the optimum arrangement of an open resonator on the electron orbit. The output depends sharply on the arrangement, and the maximum output is observed when the resonator axis intersects the electron orbit with the angle of 3°
Determination of strain-induced valence-band splitting in GaAsN thin films from circularly polarized photoluminescence
The paper studies the circularly polarized photoluminescence (PL) from dilute GaAsN alloys with nitrogen content of 1%–3.4%, grown on GaAs substrates. The room-temperature PL is found to consist of two bands whose splitting grows with increasing nitrogen content. The analysis of the PL circular polarization has shown that the PL bands originate from the splitting of light- and heavy-hole subbands, induced by an elastic strain in GaAsN layer. The dependence of the energy gap of unstrained GaAsN on the nitrogen content has been calculated using the measured light- and heavy-hole splittings
First-principles calculations of the self-trapped exciton in crystalline NaCl
The atomic and electronic structure of the lowest triplet state of the
off-center (C2v symmetry) self-trapped exciton (STE) in crystalline NaCl is
calculated using the local-spin-density (LSDA) approximation. In addition, the
Franck-Condon broadening of the luminescence peak and the a1g -> b3u absorption
peak are calculated and compared to experiment. LSDA accurately predicts
transition energies if the initial and final states are both localized or
delocalized, but 1 eV discrepancies with experiment occur if one state is
localized and the other is delocalized.Comment: 4 pages with 4 embeddded figure
Millisecond-range electron spin memory in singly-charged InP quantum dots
We report millisecond-range spin memory of resident electrons in an ensemble
of InP quantum dots (QDs) under a small magnetic field of 0.1 T applied along
the optical excitation axis at temperatures up to about 5 K. A pump-probe
photoluminescence (PL) technique is used for optical orientation of electron
spins by the pump pulses and for study of spin relaxation over the long time
scale by measuring the degree of circular polarization of the probe PL as a
function of pump-probe delay. Dependence of spin decay rate on magnetic field
and temperature suggests two-phonon processes as the dominant spin relaxation
mechanism in this QDs at low temperatures.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let
The phase-separated states in antiferromagnetic semiconductors with polarizable lattice
The possibility of the slab or stripe phase separation (alternating
ferromagnetic highly- conductive and insulating antiferromagnetic layers) is
proved for isotropic degenerate antiferromagnetic semiconductors. This type of
phase separation competes with the droplet phase separation (ferromagnetic
droplets in the antiferromagnetic host or vice versa). The interaction of
electrons with optical phonons alone cannot cause phase-separated state with
alternating highly-conductive and insulating regions but it stabilizes the
magnetic phase separation. The magnetostriction deformation of the lattice in
the phase-separated state is investigated.Comment: 17 Pages, 1 EPS Figur
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