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1.
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
2.
V. V. Afrosimov A. A. Basalaev V. V. Kuz’michev M. N. Panov O. V. Smirnov 《Technical Physics》2016,61(3):342-348
The relative cross sections of elementary processes occurring in single collisions of tryptophan molecules in the gaseous phase with He2+ ions with energy 4 keV/u are measured using time-of-flight mass spectrometry for studying the mechanism of radiation damage of amino acid molecules. The fragmentation channels for intermediate singly and doubly charged tryptophan molecular ions formed during one-electron capture, two-electron capture, and electron capture with ionization are investigated. Significant difference is observed in the mass spectra of fragmentation of intermediate doubly charged ions formed during the capture with ionization and double capture, which is associated with different energies of excitation of {C11H12N2O2}2+* ions. 相似文献
3.
Ionization and single electron capture in collision of highly charged Ar16+ ions with helium
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This paper uses the two-centre atomic orbital close-coupling method to study the ionization and the single electron capture in collision of highly charged Ar^16+ ions with He atoms in the velocity range of 1.2-1.9 a.u.. The relative importance of single ionization (SI) to single capture (SC) is explored. The comparison between the calculation and experimental data shows that the SI/SC cross section ratios from this work are in good agreement with experimental data. The total single electron ionization cross sections and the total single electron capture cross sections are also given for this collision. The investigation of the partial electron capture cross section shows a general tendency of capture to larger n and l with increasing velocity from 1.2 to 1.9 a.u.. 相似文献
4.
基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
5.
基于处理裸核离子与中性原子碰撞电离过程的OBKN和ECPSSR理论模型,系统计算了不同裸核离子与中性原子碰撞K壳层电子俘获截面和直接电离截面,并与其它文献已有的理论和实验结果进行了比较.研究结果表明:碰撞能量较低时,电子俘获截面大于直接电离截面,随着碰撞能量的增加,电子俘获截面和直接电离截面均是先增大后减小且直接电离截面减小地非常缓慢,高能时,直接电离截面大于电子俘获截面.当入射炮弹离子速度接近0.67倍靶原子K壳层电子速度时,电子俘获截面达到最大值,而当入射炮弹离子速度接近靶原子K壳层电子速度时,直接电离截面达到最大值. 相似文献
6.
V. D. Mur B. M. Karnakov V. S. Popov 《Journal of Experimental and Theoretical Physics》1998,87(3):433-444
A relativistic version of the quasiclassical imaginary-time formalism is developed. It permits calculation of the tunneling
probability of relativistic particles through potential barriers, including barriers lacking spherical symmetry. Application
of the imaginary-time formalism to concrete problems calls for finding subbarrier trajectories which are solutions of the
classical equations of motion, but with an imaginary time (and thus cannot be realized in classical mechanics). The ionization
probability of an s level, whose binding energy can be of the order of the rest energy, under the action of electric and magnetic fields of different
configuration is calculated using the imaginary-time formalism. Besides the exponential factor, the Coulomb and pre-exponential
factors in the ionization probability are calculated. The Hamiltonian approach to the tunneling of relativistic particles
is described briefly. Scrutiny of the ionization of heavy atoms by an electric field provides an additional argument against
the existence of the “Unruh effect.”
Zh. éksp. Teor. Fiz. 114, 798–820 (September 1998) 相似文献
7.
Multiple ionization of argon accompanied by electron loss and capture of 0.22-6.35 MeV C^q+ ions
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In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^+ (q = 1 - 4) ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization (or the single capture) of argon associated with single electron loss (or single electron capture) by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range. 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.
Bräuning H Mokler PH Liesen D Bosch F Franzke B Krämer A Kozhuharov C Ludziejewski T Ma X Nolden F Steck M Stöhlker T Dunford RW Kanter EP Bednarz G Warczak A Stachura Z Tribedi L Kambara T Dauvergne D Kirsch R Cohen C 《Physical review letters》2001,86(6):991-994
Strong evidence has been found for enhanced multiple electron capture into 46 MeV/u Pb81+ with a significant contribution from the entrance surface of thin carbon foils. Capture of up to five electrons has been observed. The multiple electron capture yield is found to increase with decreasing target thickness for thin targets. A simple model describing the data and showing the importance of capture from surfaces is discussed. Further evidence is found for a pronounced asymmetry between electron capture at the entrance and the exit surfaces. Absolute yields for multiple electron capture and projectile ionization are presented. The experimental total cross sections for single capture and ionization agree well with theory. 相似文献
10.
An expression for n-photon cross-section ionization of hydrogenic atoms by intense linearly polarized light is obtained using the second quantification formalism for the radiation and the Green's function method. It is shown that it reduces into Stobbe's formula in the one photon case. 相似文献
11.
B. Coupier B. Farizon M. Farizon M.J. Gaillard F. Gobet N.V. de Castro Faria G. Jalbert S. Ouaskit M. Carré B. Gstir G. Hanel S. Denifl L. Feketeova P. Scheier T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):459-468
Ionization and fragmentation of water and uracil molecules was studied both by electron and proton impact. A special coincidence
technique allows on an event by event basis the investigation of product ions formed upon the collision of protons with neutral
molecules including the identification of the charge state of the projectile. This enables the characterization of the ionization
processes occurring, i.e. direct ionization, single electron capture or double electron capture for 0, 1 or 2 electrons that are transferred from the
target to the projectile, respectively. For uracil the fragmentation patterns obtained by electron and proton impact ionization
reveal close similarities and indicate a comparable amount of excitation for the two different ionization mechanisms at high
enough projectile energies.
Received 25 February 2002 Published online 13 September 2002 相似文献
12.
A formalism is proposed for treating the problem of ionization of adsorbed species on solid surfaces. The ionizing agents are taken to be impact atoms and laser radiation with frequency low compared to the inverse of characteristic collision times. The physical constraints of short collision times and low laser frequency then allow one to treat the adatom-surface-plus-field system under the quasi-static approximation (QSA) and the impact-atom-adatom-surface collision dynamics under the impulse approximation (IMA). The latter leads to a time-dependent ionization cross-section which is factorizable into the square of an electron-atom scattering matrix element and a spectral function describing the energy-momentum distribution of electrons in the adatom-surface-plus-field system. The formalism focuses on the spectral function which is shown to be derivable from a single-particle Green's function exactly calculable for the present problem. 相似文献
13.
We present cross sections for electron-impact ionization and simultaneous ionization plus excitation of helium by electron impact. The results are obtained from a fully nonperturbative close-coupling formalism using our B-spline R-matrix approach. A large number of pseudostates in the expansion of the wave function represent the coupling to the ionization continuum. We obtain excellent agreement with the directly measured experimental cross section ratios (Bellm et al., Phys. Rev. A 75, 042704 (2007)) for ionization leaving the residual He? ion in either the 1s ground state or the n = 2 (2s + 2p) excited states. 相似文献
14.
15.
V. V. Afrosimov A. A. Basalaev K. V. Kashnikov M. N. Panov 《Physics of the Solid State》2002,44(3):509-510
This paper reports on the first measurements of the differential cross sections (with respect to scattering angle) of various elementary processes accompanying electron capture by keV-range H+ and He2+ ions from a fullerene molecule. Estimation of the impact parameter from the ion scattering angle in the polarization interaction with a fullerene molecule shows that the processes of capture and capture with fullerene ionization and fragmentation occur primarily at impact parameters far exceeding the fullerene radius. 相似文献
16.
H. Deutsch K. Becker P. Defrance M. Probst J. Limtrakul T. D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(3):489-493
New measurements of the cross-section for electron impact ionization of the
molecular ion C2H2+ have been carried out recently. These
data differ significantly from earlier data, because cross-sections
corresponding to all the possible dissociative ionization processes were
determined. The new data in conjunction with the significant discrepancies
between the earlier data and the results of various calculations, which
disagreed among themselves by a factor of 3, motivated a renewed attempt to
apply the semi-classical Deutsch-M?rk (DM) formalism to the calculation
of the absolute electron-impact ionization cross-section of this molecular
ion. A quantum chemical molecular orbital population analysis for both the
neutral molecule and the ion revealed that in the case of
C2H2+ the singly occupied molecular orbital (i.e. the
“missing” electron) is highly localized near the site of a C atom in the
molecule. This information is explicitly incorporated in our formalism. The
results obtained by taking the ionic character directly into account are in
excellent agreement with the recent experimental data. 相似文献
17.
A new formalism for the calculation of field ionization rate-constants near a model metal surface is derived. Approximate analytic formulae are given for the ionization rate-constant of an atom as a function of distance from the metal surface, for the total probability of ionization on a single pass through the ionization zone and for the width of the ionization zone. Theoretical estimates of best image fields are given for gas atoms of interest in field ion microscopy. The clarity of approach and computational ease of the method is shown to be compatible with the production of acceptably accurate results. 相似文献
18.
It is pointed out that the superoperator formalism, developed for the calculation of ionization potentials in molecular physics, is a very powerful tool in chemisorption theory. This is demonstrated by applying the formalism to the Anderson-Newns model and by showing how the different approximate solutions can be obtained by elegant and systematic procedures. It is also pointed out that using the formalism, solutions for more complicated hamiltonians can easily be obtained. 相似文献
19.
The modified Jain–Khare semi-empirical formalism for the evaluation of differential and integral electron impact ionization cross sections for molecules has been extended to the evaluation of cross sections for the electron ionization of CO2 clusters: (CO2)240 and (CO2)1700. The energy dependent differential cross sections are evaluated at the incident electron energies of 50, 100 and 200 eV. The integral total ionization cross sections have been calculated in the energy range varying from ionization thresholds to 1000 eV which revealed a good agreement with the available experimental and the theoretical data. The ionization rate coefficients have also been evaluated using the presently calculated ionization cross sections and Maxwell–Boltzmann energy distributions. 相似文献
20.
Single-electron capture from the K shell of atomic targets by impact of protons at moderate and high energies has been studied using a first-order three-body Coulomb-Born continuum distorted wave approximation. The applied formalism satisfies the correct Coulomb boundary conditions. Single-zeta Roothaan-Hartree-Fock wave functions are used to describe the initial electronic bound state of the exchanged electron. Both differential and integral capture cross sections are calculated for impact of protons on carbon, nitrogen, oxygen, neon and argon atoms. The results are compared with the available measurements and other theories. The agreement between the calculations and experimental data is remarkable. 相似文献