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Sharp Lines (sharp + line)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Optical properties of single ZnO nanowires

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2006
L. Wischmeier
Abstract The optical properties of single ZnO nanowires with diameters <200 nm are analyzed. A comparison of the photoluminescence properties of the as-grown ensemble and of an individual nanowire is given. The temperature dependence of the individual nanowire photoluminescence shows the same behavior as that of bulk material due to the wire diameter being very large compared to the exciton Bohr radius of ZnO. Furthermore, high excitation-density measurements performed on an individual nanowire are presented in which a sharp line is observed resulting from resonator effects inside the wire. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Magneto-optical spectroscopy of (Zn,Co)O epilayers

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2006
W. Pacuski
Abstract We present a magneto-optical study of (Zn,Co)O layers grown by molecular beam epitaxy. We observed sharp lines related to 4A2,2E intra-ionic Co2+ transitions, and to the A , B and C excitons. Intra-ionic transitions observed by absorption and photoluminescence were used to determine the values of the parameters describing the isolated Co ions, such as the easy-plane magnetic anisotropy and the g -factor of the S = 3/2 Cobalt spin. Excitonic transitions observed in reflectivity were used to determine the giant Zeeman splitting and to estimate the effective coupling ,N0(, , , ),A ,B = 0.4 eV between excitons and Cobalt spins. Due to the electron,hole exchange within the exciton, this effective spin,exciton coupling is much weaker than the exchange integrals for free carriers, estimated to be N0|, , , | , 0.8 eV, with a positive value of (, , , ) if the normal ordering of the valence band of ZnO is assumed. The Zeeman splitting of diluted samples and the magnetic circular dichroism (for a higher Co content) are proportional to the magnetization of the paramagnetic, isolated Cobalt ions. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Photoluminescence study of isoelectronic traps in dilute GaAsN alloys

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007
H. Yaguchi
Abstract We have studied photoluminescence spectra in detail to clarify the character of the isoelectronic traps in dilute GaAsN alloys. Several sharp lines have been observed at the lower energy side of the GaAs bandgap and are in good agreement with the nitrogen pair-related emission lines previously reported. In addition to the nitrogen pair-related lines, some other emission lines have been also observed. Compared with the energies of these emission lines and the nitrogen pair-related emission lines, it was found that the energy differences agree with the longitudinal optical phonon energy at the , point of GaAs, showing that the character of isoelectronic traps due to nitrogen pairs in dilute GaAsN alloys is significantly contributed from the conduction band state at the , point. The temperature dependence of the peak energy of luminescence due to nitrogen pairs also indicates that the character of isoelectronic traps in dilute GaAsN alloys is due to the conduction band edge state at the , point of GaAs. For a dilute GaAsN alloy with lower nitrogen concentration, we have observed that the intensity of an emission line increased superlinearly with excitation power . (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Reduction of Nitrogen on Gallium Phosphide Nanoparticles

CHINESE JOURNAL OF CHEMISTRY, Issue 9 2005
Zhao-Chun Zhang
Abstract Under mild ambient conditions gallium phosphide (GaP) nanoparticles were employed to carry out the reduction of nitrogen. By using Nessler's reagent ammonia was detected in the slurry where the aggregated GaP particles were suspended in water and bubbled by pure nitrogen. Dependence of the concentration of ammonia upon bubbling time, velocity of the flow of nitrogen, and dosage of GaP particles was investigated. In comparison with the original GaP nanoparticles, the Raman scattering of the GaP particles undergoing the process of nitrogen fixation reveals that two sharp lines at 138 and 182 cm -1, respectively, emerged from the broad continuum around 100,200 cm -1. These two lines might be assigned to the translational motions of ammonia adsorbed on the surface of the GaP particles. An assessment of the infrared spectra of the two GaP particles led to the conclusion that the environment of the two H2O molecules was not identical. Analysis of the electron spin resonance results showed that the structure defect, gallium self-interstitial, was not involved in the nitrogen fixation of the GaP nanoparticles. [source]