A novel laser-based apparatus is presented utilizing high harmonic radiation for visible pump–EUV probe experiments on ultrafast processes. True femtosecond temporal resolution is achieved by a monochromator making use of dedicated narrowband multilayer mirrors rather than gratings for selection of single harmonic orders in the photon energy range between 66 and 73 eV. First applications of this new light source for electron spectroscopy on gas phase helium and xenon demonstrate the selection of a single high harmonic order with the intensity ratio between the selected and its adjacent harmonic not exceeding 10:1. A pump–probe study of hot electron production on a solid Pt(110) surface yields a cross-correlation corresponding to a temporal system resolution of 100 fs.
In the coherent electron cooling, the modern hadron beam cooling technique, each hadron receives an individual kick from the electric field of the amplified electron density perturbation created in the modulator by this hadron in a copropagating electron beam. We developed a method for computing the dynamics of these density perturbations in an infinite electron plasma with any equilibrium velocity distribution-a possible model for the modulator. We derived analytical expressions for the dynamics of the density perturbations in the Fourier-Laplace domain for a variety of 1D, 2D, and 3D equilibrium distributions of the electron beam. To obtain the space-time dynamics, we employed the fast Fourier transform algorithm. We also found an analytical solution in the space-time domain for the 1D Cauchy equilibrium distribution, which serves as a benchmark for our general approach based on numerical evaluation of the integral transforms and as a fast alternative to the numerical computations. We tested the method for various distributions and initial conditions.
The behaviour of copper dopant in p-Hg 1−x Cd x Te single crystals is analysed for in-diffusion in the samples with heterogeneous distribution of Hg vacancies and for ion beam milling. For the case of low Hg vacancy, p-Hg 1−x Cd x Te (x ∼ 0.2) material, copper is found to diffuse by a relay-race interstitial mechanism at low temperature. When the Cu-doped p-Hg 1−x Cd x Te samples are exposed to ion milling, the p-n conversion of conductivity type occurs in a substantially thick subsurface layer (∼10 µm). Unstable donor centres such as copper in interstitials rapidly relax so that residual donors control the conductivity in a converted layer after several hours. The possible causes of the incomplete p-type reconversion are discussed.
The angular anisotropy parameters of the Auger decay α2 and spin polarization parameters β2 were calculated for Na, Kr, Xe, Ba, and Hg using the multichannel Dirac–Fock method. These calculations were performed using LSJ and relativistic intermediate coupling. The exchange effect was used in all calculations. We showed numerically that orbital relaxation during the Auger decay had only a small effect on the angular distribution for open-shell atoms. The obtained values for α2 and β2 were compared with other theoretical results.
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