143,359 research outputs found
Compositional changes on GaN surfaces under low-energy ion bombardment studied by synchrotron-based spectroscopies
We have investigated compositional changes on GaNsurfaces under Ar-ion bombardment using synchrotron-based high-resolution x-rayphotoemission (PES) and near-edge x-ray absorption fine structure(NEXAFS)spectroscopy. The low-energy ion bombardment of GaN produces a Ga-rich surface layer which transforms into a metallic Ga layer at higher bombarding energies. At the same time, the photoemissionspectra around Nâ1s core levels reveal the presence of both uncoordinated nitrogen and nitrogen interstitials, which we have analyzed in more details by x-rayabsorption measurements at NâK edge. We have demonstrated that PES and NEXAFS provide a powerful combination for studying the compositional changes on GaNsurfaces. A mechanism for the relocation and loss of nitrogen during ion bombardment in agreement with some recent experimental and theoretical studies of defect formation in GaN has been proposed.P.N.K.D. is grateful for the financial
support of the Australian Research Council
The Next-to-Leading BFKL Pomeron with Optimal Renormalization
The next-to-leading order (NLO) corrections to the BFKL equation in the BLM
optimal scale setting are briefly discussed. A striking feature of the BLM
approach is rather weak Q^2-dependence of the Pomeron intercept, which might
indicate an approximate conformal symmetry of the equation. An application of
the NLO BFKL resummation for the virtual gamma-gamma total cross section shows
a good agreement with recent L3 data at the CERN LEP2.Comment: 5 pages, 1 eps-figure, to appear in Proceedings of VIIIth Blois
Workshop at IHEP, Protvino, June 28 - July 2, 199
The Next-to-Leading Dynamics of the BFKL Pomeron
The next-to-leading order (NLO) corrections to the BFKL equation in the BLM
optimal scale setting are briefly discussed. A striking feature of the BLM
approach is rather weak Q^2-dependence of the Pomeron intercept, which might
indicate an approximate conformal symmetry of the equation. An application of
the NLO BFKL resummation for the virtual gamma-gamma total cross section shows
a good agreement with recent L3 data at CERN LEP2 energies.Comment: 7 pages, 2 eps-figures, presented at International Symposium on
Multiparticle Dynamics (ISMD99), August 9-13, 1999, Brown University,
Providence, Rhode Islan
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