Excitation of K-shell electrons into<i>n</i>s states by the impact of charged particles

Nefiodov, A. V.; Plunien, G.

doi:10.1088/0953-4075/43/16/165206

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…For large values of l, the cross section is very small the relative error in estimating the cross section with the scaling law gets increased. It is to be mentioned here that the cross section for electron impact excitation and rearrangement processes also follows a 1/n 3 type scaling law [32,[36][37][38][39]. But in that case the scaling factor is rather different.…”

Section: Discussionmentioning

confidence: 88%

“…This prevented the earlier workers from attempting the study of such problems until recently. Results for positron-hydrogen inelastic scattering are mostly reported for 1s → 2s and 1s → 2p transitions [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], except a few [28][29][30][31][32]. Recently, Ghoshal and Mandal [30] and Nayek and Ghsohal [31] investigated ns → n s transitions of the hydrogen atom by positron impact.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rydberg transitions for positron–hydrogen collisions: asymptotic cross section and scaling law

Rej

Ghoshal²

2013

J. Phys. B: At. Mol. Opt. Phys.

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The dynamics of 1s → nlm excitations of hydrogen, for arbitrary n, l, m, by positron impact has been investigated using a distorted-wave theory in the momentum space. It has been possible to obtain the distorted-wave scattering amplitude in a closed analytical form. A detailed study has been made on the differential and total cross sections in the energy range 20-300 eV of incident positron. A simple law has been presented for obtaining asymptotic cross sections for excitation into different angular momentum states. To the best of our knowledge, such a study on the differential and total cross sections for 1s → nlm inelastic positron-hydrogen collisions using distorted-wave theory is the first reported in the literature.

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Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Rydberg transitions for positron–hydrogen collisions: asymptotic cross section and scaling law

Rej

Ghoshal²

2013

J. Phys. B: At. Mol. Opt. Phys.

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“…For the lower autoionizing states, the asymptotic high-energy limits amount to the values B 1 = 0.0231 and B 2 = 0.0072. * Work supported by GSI Then for fast projectiles (ε 3/2), the total cross sections have a simple scaling behavior like σ * * ∼ ε −1 , which is similar to that for single-electron excitations 1s → ns [2]. Note, that in this case, the formula (1) can also be employed for collisions with heavy charged particles, which are nevertheless much lighter than the atomic nucleus of target.…”

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confidence: 70%

Excitation of autoionizing states of helium-like ions by scattering of high-energy particles

Михайлов

Nefiodov

et al. 2013

J. Exp. Theor. Phys.

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Two-electron excitations of atoms and ions induced by impact of charged particles and photons are fundamental processes, which have been studied since decades. Along with double ionization and ionization accompanied by simultaneous excitation, double excitation is caused by the interelectronic interaction. Accordingly, the cross sections of these processes turn out to be extremely sensitive to the quality of which dynamic correlations are taken into account. This allows one to test different theoretical approaches. In experiments, the neutral helium atom is perferably used as a target, since it is the simplest multielectron system. Helium-like ions with moderate values of nuclear charge Z are even more attractive for investigation of correlated processes, since the corresponding cross sections exhibit a universal scaling behavior. However, such processes are rather rare. Their cross sections decrease rapidly with increasing Z values.In a most recent paper [1], we have studied two-electron excitations of helium-like ions into the two lower autoionizing 2s 2 ( 1 S) and 2p 2 ( 1 S) states (in the following denoted, for simplicity, by numbers 1 and 2, respectively) by collisions with high-energy electrons and photons. The calculations are performed analytically within the framework of non-relativistic perturbation theory with respect to the interelectronic interaction. The atomic targets are assumed to be characterized by the small parameters 1/Z 1 and αZ 1, where α is the fine-structure constant. The Auger widths of the levels are equal to Γ 1 = 0.226 eV and Γ 2 = 0.011 eV.In high-energy non-relativistic domain characterized by 3/2 ε 2(αZ) −2 , the total cross section can be cast into the following scaling form ( = 1, c = 1) [1]:where σ 0 = πa 2 0 = 87.974 Mb and a 0 = 1/(mα) is the Bohr radius. The limits of integration over the dimensionless momentum transfer x are given by x 1 = 9/(4x 2 ) and x 2 = ( √ ε + ε − 3/2) 2 , respectively. The dimensionless energy ε is related to the asymptotic velocity v of projectile according to ε = v 2 /(αZ) 2 . The universal functions Q(x) and B(ε) are independent of the values of Z. The excitation process is characterized by a rather small momentum transfer x 4 (see Fig. 1). The scalings B(ε) are saturated already at ε 10. For the lower autoionizing states, the asymptotic high-energy limits amount to the values B 1 = 0.0231 and B 2 = 0.0072. * Work supported by GSI Then for fast projectiles (ε 3/2), the total cross sections have a simple scaling behavior like σ * * ∼ ε −1 , which is similar to that for single-electron excitations 1s → ns [2]. Note, that in this case, the formula (1) can also be employed for collisions with heavy charged particles, which are nevertheless much lighter than the atomic nucleus of target. If the charge number of the incident particle is equal to ±z (in units of the elementary charge e), then the cross section should be multiplied by the factor z 2 . Although Γ 2 Γ 1 , both the autoionizing 2s 2 ( 1 S) and 2p 2( 1 S) levels can be efficiently excited b...

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“…2 p transitions, except a few. [40][41][42][43][44] Because, in general, carrying out a sophisticated quantum mechanical calculation involving highly excited states is complicated in practise due to the presence of a large number of oscillations in the final bound state wave function. In presence of plasma medium, calculations get further complicated due to the lack of knowledge of the exact hydrogenic wave function in plasma.…”

Section: Introductionmentioning

confidence: 99%

Positron impact excitations of hydrogen atom embedded in dense quantum plasmas: Formation of Rydberg atoms

Rej

Ghoshal

2014

Physics of Plasmas

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Formation of Rydberg atoms due to 1 s ! nlm excitations of hydrogen by positron impact, for arbitrary n, l, m, in dense quantum plasma has been investigated using a distorted wave theory which includes screened dipole polarization potential. The interactions among the charged particles in the plasma have been represented by exponential cosine-screened Coulomb potentials. Making use of a simple variationally determined hydrogen wave function, it has been possible to obtain the distorted wave scattering amplitude in a closed analytical form. A detailed study has been made to explore the structure of differential and total cross sections in the energy range 20-300 eV of incident positron. For the unscreened case, our results agree nicely with some of the most accurate results available in the literature. To the best of our knowledge, such a study on the differential and total cross sections for 1 s ! nlm inelastic positron-hydrogen collisions in dense quantum plasma is the first reported in the literature. V C 2014 AIP Publishing LLC.

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Excitation of K-shell electrons intons states by the impact of charged particles

Cited by 3 publications

References 17 publications

Rydberg transitions for positron–hydrogen collisions: asymptotic cross section and scaling law

Rydberg transitions for positron–hydrogen collisions: asymptotic cross section and scaling law

Excitation of autoionizing states of helium-like ions by scattering of high-energy particles

Positron impact excitations of hydrogen atom embedded in dense quantum plasmas: Formation of Rydberg atoms

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