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1.
《Physics letters. A》2019,383(21):2488-2491
We calculated the cross sections of ultra-soft x-ray bremsstrahlung in electron scattering upon Ar, Kr and Xe. The results are consistent with the absolute values of the differential cross sections measured by Gnatchenko et al. (2009) [17] for scattering electrons with an energy of 600 eV on these atoms. 相似文献
2.
Technical Physics - We have measured the absolute values of total cross sections of capture of one and two electrons by He2+ ions from argon atoms. The differential scattering cross sections have... 相似文献
3.
The absolute differential cross sections of scattering of hydrogen atoms resulting from an electron capture and an electron capture ionization are measured for collisions of 4.5- and 11-keV protons with argon and xenon atoms. The range of scattering angles is 0°–2°. From the scattering differential cross section found experimentally, the probabilities of single-electron capture and electron capture ionization as a function of the impact parameter are calculated. The dependences of the incident particle scattering angle on the impact parameter (deviation function) for interactions with Ar and Xe atoms are calculated in terms of classical mechanics using the Moliére—Yukawa potential to describe the interaction of atomic particles. Analysis is given to the probabilities of electron capture and electron capture ionization versus the impact parameter and to the distribution of the electron density on different electron shells in a target atom versus a distance to the core. It is concluded that only electrons from the outer shell of the target atom are involved in the process of electron capture ionization. The cross section of electron capture ionization is calculated in the proton energy range 5–20 keV. 相似文献
4.
Absolute doubly differential bremsstrahlung cross sections from Xe, Kr, Ar, and Ne have been measured for electron bombarding energies of 28 and 50 keV. Bremsstrahlung photons have been detected at 90 degrees to the incident electron beam at energies ranging from 5 keV up to the kinematic end point. The results are compared with predictions of ordinary bremsstrahlung and of total bremsstrahlung that include polarizational bremsstrahlung from the target atom calculated in the stripping approximation. All previous absolute cross sections have been from thin-film solid targets and have not shown any polarizational bremsstrahlung contribution. The present results, the first from free atoms, provide definitive evidence for the contribution of polarizational bremsstrahlung to the photon spectrum from electron bremsstrahlung. 相似文献
5.
Coincidence measurements of the absolute cross section for the production of bremsstrahlung by electrons in the field of gold atoms are reported. The incident electron energyT 0 was 300 keV. Measurements were made for four different combinations of electron scattering angle and photon emission angle over a wide range of the relative photon energyk/T 0 up tok/T 0=0.83. The measured cross sections are compared with results of Bethe-Heitler and Elwert-Haug calculations 相似文献
6.
Effective-range theory is developed to describe the processes of multiphoton bremsstrahlung absorption and the emission of laser radiation that accompanies the scattering of electrons from atoms in a laser field. It is found that the cross sections for multiphoton absorption in the plateau region increases resonantly for electron energies corresponding to the thresholds of induced bremsstrahlung (i.e., multiples of the photon energy). It is shown that this effect is caused by the laser-field modified threshold phenomena in the cross sections for multichannel reactions (Baz’ threshold anomalies). 相似文献
7.
A. V. Korol’ A. G. Lyalin O. I. Obolenskii A. V. Solov’ev 《Journal of Experimental and Theoretical Physics》1998,87(2):251-259
This paper develops an effective method for calculating the bremsstrahlung cross section with allowance for the polarization
mechanism. We calculate the cross section of bremsstrahlung produced in the scattering of electrons and positrons by H and
Kr atoms. We also demonstrate the important role of polarization bremsstrahlung in the formation of the total emission spectrum
over the entire frequency range.
Zh. éksp. Teor. Fiz. 114, 458–473 (August 1998) 相似文献
8.
We have measured the absolute values of the total cross section of the one-electron capture by He2+ ions in the kinetic energy range 2–30 keV at the Ar atoms. The absolute values of the differential scattering cross sections of He+ ions formed during the one-electron capture and the electron capture with ionization at energies of 2.2, 5.4, and 30 keV have been determined. The electronic states of the formed ions have been determined using collision spectroscopy based on analysis of the change in the kinetic energy of He+ after the interaction. We have measured doubly differential (with respect to the kinetic energy and the scattering angle) cross sections of the formation of free electrons. The free electron formation channels (direct ionization and electron capture with ionization) have been analyzed by calculating the electron terms of the (HeAr)2+ system. The calculated cross section of capture with ionization is in conformity with the cross section measured using collision spectroscopy. 相似文献
9.
10.
E. Haug 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(1):57-61
The differential cross section of bremsstrahlung emitted in the head-on
collision of beams of energetic protons and electrons is calculated in
the laboratory frame. The angular distribution of the photons is more
isotropic than in the common bremsstrahlung production on stationary
target atoms. The total cross section is determined by integration over
the photon angles which are allowed kinematically. 相似文献
11.
A relatively new computational technique, namely gradient tree boosting (GTB), is presented for modeling the total cross sections
of the scattering of positrons and electrons by alkali atoms in the low and intermediate energy regions. The calculations
have been performed in the framework of gradient tree boosting (GTB). The GTB has been running based on the experimental data
of the total collisional cross sections to produce the total cross sections for each alkali atom as a function of the incident
energy of the projectile as well as the atomic number and the static dipole polarizability of the atom. Moreover our GTB model
is used to predict the experimental data for total collisional cross sections that are not used in the training session. The
calculated and predicted total collisional cross sections are compared with the experimental data. We find that the GTB technique
shows a good match to the experimental data. To our knowledge, this is the first application of the GTB technique to the data
of positron and electron collisions with alkali atoms at low and intermediate energies. 相似文献
12.
W. A. A. Macedo V. R. P. R. O. Marciano J. M. Correia Neves D. P. Svisero 《Hyperfine Interactions》1994,83(1):483-487
We have measured total cross sections for 5–302 eV positrons and 31–302 eV electrons scattered by atomic hydrogen using a beam-transmission technique. Atomic hydrogen obtained from a radio frequency (rf) discharge source flows into an aluminium scattering cell maintained at about 150 K to minimize recombination. Absolute total cross sections are obtained by making relative measurements for positrons and electrons scattering from H2 and a known mixture of H and H2, and then normalizing the measurements for positron-H2 scattering to prior absolute measurements. Our total cross section measurements for positrons and electrons scattering from H are found to be merged to within 5% for energies from 31 to 302 eV. 相似文献
13.
R. Müller-Fiedler P. Schlemmer K. Jung H. Ehrhardt 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(1):89-94
Triple differential cross sections have been measured for electron impact ionization of helium at 256 eV collision energy, 3 eV energy of the slow outgoing electrons and scattering angles of the fast outgoing electrons of 4°, 6°, 8°, and 10°. The data have been put on absolute scale by extrapolating the generalized oscillator strength to zero momentum transfer. In this optical limit the triple differential cross sections can be normalized by using the well-known cross sections for photoionization. The experimental data are compared with results of different theoretical approaches. For nearly all calculated curves rather good agreement with the measurements is obtained for the relative shape of the binary peak, while often its absolute cross section is overestimated. Concerning the recoil peak, larger discrepancies are found with respect to both, relative shapes and cross sections. A perceptible improvement can be stated for calculations which have been performed in a distorted wave approximation and in second Born approximation. 相似文献
14.
A modification potential method of calculating total cross sections of electrons scattering from complex molecules C2H6, C2F6, C6H6 and C6F6 at 100 eV-5000 eV
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A complex optical model potential modified by
incorporating the concept of bonded atom, which takes into consideration the
overlapping effect of electron clouds between two atoms in a molecule, is
first employed to calculate the total cross sections for electrons
scattering from such complex molecules as C总交叉断面 电子散射 添加规则 原子分子碰撞 电子云 total cross section, electrons scattering, additivity
rule, atomic and molecular collision Project supported by the National Natural Science Foundation of China (Grant No 10574039). 2005-11-10 2005-11-102005-11-30 A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is first employed to calculate the total cross sections for electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 using the aclditivity rule model at Hartree-Fock level over the energy range from 100 eV to 5000 eV. The total cross sections are quantitatively compared with those obtained by experiments wherever available, and they are in good agreement with each other over a wide energy range. It is shown that the modified potential together with the additivity rule model is completely suitable for the calculation of total cross sections of electrons scattering from such complex molecules as C2H6, C2F6, C6H6 and C6F6 above 200 eV-300 eV. 相似文献
15.
Interference effects on the photoionization cross sections between two neighbouring atoms: nitrogen as an example
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Interference effects on the photoionization cross sections
between two neighbouring atoms are considered based on the coherent
scattering of the ionized electrons by the two nuclei when their
separation is less than or comparable to the de Broglie wave length
of the ionized electrons. As an example, the single atomic nitrogen
ionization cross section and the total cross sections of two
nitrogen atoms with coherently added photoionization amplitudes are
calculated from the threshold to about 60~\AA (1~\AA=0.1~nm) of the
photon energy. The photoionization cross sections of atomic nitrogen
are obtained by using the close-coupling R-matrix method. In the
calculation 19 states are included. The ionization energy of the
atomic nitrogen and the photoionization cross sections agree well
with the experimental results. Based on the R-matrix results of
atomic nitrogen, the interference effects between two neighbouring
nitrogen atoms are obtained. It is shown that the interference
effects are considerable when electrons are ionized just above the
threshold, even for the separations between the two atoms are larger
than two times of the bond length of N2 molecules. Therefore, in
hot and dense samples, effects caused by the coherent interference
between the neighbours are expected to be observable for the total
photoionization cross sections. 相似文献
16.
在考虑分子内原子间的几何屏蔽效应随电子入射能量变化的基础上, 提出了一种能够在中、高能区准确计算“电子-分子”散射总截面的可加性规则修正方法. 利用这一修正后的可加性规则并使用“电子-C, H, O, N原子”散射总截面的实验数据, 在50—5000 eV内计算了电子被NO, N2O, NO2和C2H6分子散射的总截面, 且将计算结果与实验结果及其他理论结果进行了比较. 结果表明, 利用这一方法修正过的可加性规则进行计
关键词:
电子散射
可加性规则
总截面
几何屏蔽效应 相似文献
17.
18.
P. Syty Ł. Redynk J. E. Sienkiewicz 《The European physical journal. Special topics》2013,222(9):2323-2328
In this contribution we describe the multichannel extension to the nonrelativistic J-matrix method, and present differential cross sections for scattering of slow electrons from Argon atoms. Nonrelativistic phase shifts, then the S-matrix and the cross sections have been calculated using newly developed Fortran code, JMATRIX-MULTI. We applied the model Hartree-Fock potential as the scattering potential, which was truncated in the oscillatory basis functions. 相似文献
19.
I. M. Naddzhafov M. R. Radzhabov N. I. Naddzhafov A. M. Gasimova 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(9):1296-1300
The process of polarized bremsstrahlung of electrons in crystals has been theoretically investigated with application of the
new method taking into account the screening of the Coulomb nucleus field by atomic electrons. Real changes in the cross sections
of both polarized and unpolarized bremsstrahlung and the degrees of particle polarization in a silicon crystal are obtained. 相似文献
20.
X. Q. Xi J. B. Gong T. Zhang R. H. Yue W. M. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):193-199
For the process of electron-electron (e-e) bremsstrahlung the momentum and energy distributions of the recoiling electrons
are calculated in the laboratory frame. In order to get the differential cross section and the photon spectrum for target
electrons which are bound to an atom, these formulae are multiplied by the incoherent scattering function and numerically
integrated over the recoil energy. The effect of atomic binding is most pronounced at low energies of the incident electrons
and for target atoms of high atomic numbers. The results are compared to those of previous calculations. 相似文献