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101.
Ashcroft’s analytic bare ion pseudopotential form factor with a modified Hartree dielectric function has been employed to
represent the temperature dependent interionic potential. This potential includes both direct ion-ion interaction and indirect
ion-electron-ion interaction with and without the effects of ‘d’ bands, in some scantily studied complexbcc metals vizbcc Ti, Zr and Hf. The ab initio radial and tangential force constants extending out to 15th nearest neighbours are computed
for the metals. The said potential is used for predicting the binding energy, elastic constants and phonon dispersion of the
above mentioned metals and the results are satisfactorily compared with the corresponding measured data. 相似文献
102.
Progress in high resolution Auger electron spectroscopy (HR-AES or scanning Auger microscopy, SAM) during the past few years is characterized by the use of efficient field emission electron sources, parallel detection capabilities and improved data acquisition, storage and processing, thus enhancing spatial resolution (to about 10 nm), signal to noise figure and quantification of elements in different chemical bonding states, e.g. by routinely using factor analysis. Optimized ion sputtering facilities, particularly sample rotation, enable depth profiling with high, depth independent resolution. The basic features of SAM are discussed with respect to EPMA (electron probe micro-analysis), emphasizing fundamental limitations and future developments. 相似文献
103.
N. Betz A. Le Moël E. Balanzat J. M. Ramillon J. Lamotte J. P. Gallas G. Jaskierowicz 《Journal of Polymer Science.Polymer Physics》1994,32(8):1493-1502
Poly(vinylidene difluoride) (PVDF) films were irradiated by means of heavy ions (in the electronic stopping-power range) and electrons. Both types of ionizing radiation induce in the polymer film ionizations and excitations, but swift heavy ions induce a huge density of excitations and ionizations along the ion path. Dose-range goes from 0.3 to 40 MGy. Irradiations were performed with Kr ions in the presence of helium, hydrogen, deuterium, and oxygen. Fourier transform infrared (FTIR) transmission measurements show differences in the nature of the created defects. Triple bonds are characteristic of the Kr ion irradiation. Double bonds, isolated and conjugated, exist for both kinds of radiation, but concentrations are higher with the Kr radiation. The presence of oxygen during irradiation produces oxidization defects. Typical bands of hydroxyls and carbonyls can be seen, respectively, in the 3800-3000 cm?1 zone and ca. 1850–1730 cm?1. The formation of conjugated double bonds is enhanced when the Kr irradiation is performed under an O2 atmosphere. © 1994 John Wiley & Sons, Inc. 相似文献
104.
Photo-induced electron emission from 17beta-estradiol and progesterone and possible biological consequences 总被引:1,自引:0,他引:1
Getoff N Hartmann J Huber JC Quint RM 《Journal of photochemistry and photobiology. B, Biology》2008,92(1):38-41
It was established for the first time, that the sexual hormones 17beta-estradiol (17betaE2) and progesterone (PRG) are able to emit electrons from their excited single state in water-ethanol mixtures. The yield of the "solvated electrons" (e(s)(-)) depends on the substrate concentration, the ratio of water-alcohol-mixtures and the temperature. The e(s)(-) yield obtained from 17betaE2 is by two orders of magnitude higher than this of PRG. The possible relationship of the resulting hormone transients from 17betaE2 leading via specific metabolites to breast cancer is discussed. 相似文献
105.
J. Piasecki 《Journal of statistical physics》1981,24(1):45-58
The Lorentz gas of charged particles in a constant and uniform electric field is studied. The gas flows through the medium of immobile, randomly distributed scatterers. Particles with velocity v suffer collisions with frequency proportional to ¦v¦
n
. Forn < 0 runaway of the gas is forced by the field: the mean velocity of the flow increases without bounds. By a simple physical argument an integral relation is established between the probability of collisionless motion and the velocity distribution. It is then shown that whenn < –1 a fraction of particles moves as if the scattering centers were absent. The detailed discussion of this uncollided runaway is presented. Some qualitative features of the velocity distribution are illustrated on rigorous solutions in one dimension. 相似文献
106.
F. F. Karpeshin M. B. Trzhaskovskaya J. Zhang 《The European Physical Journal A - Hadrons and Nuclei》2009,39(3):341-348
A mechanism of triggering the 12.7keV E3 transition, based on the new decay mode of the 31y isomer via resonance internal conversion and emission of a 1.4keV X-ray
quantum, is considered. Actually, this decay mode was observed previously in the decay of 45- and 46-fold ions of 125Te . For the purpose of triggering, the atomic radiative vertex has to be induced by resonance radiation. This mechanism makes
triggering by an order of magnitude more efficient than triggering a bare nucleus, and is achieved at a lower combination
frequency. An experiment is proposed for the direct observation of the new decay mode. This also offers a new way of resonance
scattering of these X-rays. Triggering through higher-lying 2573 and 2805keV states is also considered. The results are extended
to the general problem of triggering. The main obstacle for enhancing the efficiency is a high internal conversion rate. For
this reason, shape isomers with low multipole order --E1 , M1 , and with a high enough energy of triggering transition are of interest for triggering. The partial ionization of the outer
electrons will also help. The same recommendations hold for triggering isomers in laser-produced plasma. 相似文献
107.
The differential cross-sections forē-helium elastic scattering are calculated by using Yateshigh-energy higher order Born approximations, through 0 (K
i
Emphasis>−2
) of the incident electron momentum, and comparisons have been made with the recent theoretical and experimental results. 相似文献
108.
M. Gupta K. L. Baluja 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):475-483
Electron-H2S collision process is studied using the R-matrix method. Nine low-lying states of H2S molecule are considered in the R-matrix formalism to obtain elastic integral, differential, momentum transfer and excitation cross sections for this scattering
system. We have represented our target states using configuration interaction (CI) wavefunctions. We obtained adequate representation
of vertical spectrum of the target states included in the scattering calculations. The cross sections are compared with the
experiment and other theoretical results. We have obtained good agreement for elastic and momentum transfer cross sections
with experiment for entire energy range considered. The differential cross sections are in excellent agreement with experiment
in the range 3–15 eV. A prominent feature of this calculation is the detection of a shape resonance in 2B2 symmetry which decays via dissociative electron attachment (DEA). Born correction is applied for the elastic and dipole allowed
transition to account for higher partial waves excluded in the R-matrix calculation. The electron energy range is 0.025–15 eV. 相似文献
109.
S. Y. Yousif Al-Mulla 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):11-14
Differential cross sections for the elastic scattering of electrons from the
ground states of
copper for the configuration 3d10 4s and the excitation state 2D
with the configuration 3d9 4s2
have been calculated. Local density approximations to the exchange and
correlation potentials
have been used in these calculations, and it is confirmed that Hara exchange
coupled with a
Hedin-Lundqvist electron-gas-type correlation potential joined to an
adiabatic polarization
potential gives good predictions for differential cross sections.
A comparison of the calculated results with other experimental and
theoretical data are presented and discussed. 相似文献
110.
S. Telega F. A. Gianturco 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):495-500
Quantum calculations of the resonant vibrational excitation of N2 by electron impact are carried out using
a model potential for exchange and correlation-polarization forces and exact static interaction. The inelastic process
is treated within a coupled channel, space-frame formulation and final cross-sections are tested for convergence within
less than
of their values. Comparison with the experiments yields very good agreement with the latter data in the resonance region
and suggests
possible extension to calculations near the threshold openings for rovibrational inelastic processes induced by electron impact. 相似文献