Collisions between rare-gas atoms at low keV energies. I. Symmetric systems

Brenot, J. C.; Dhuicq, D; Gauyacq, J.P.; Pommier, J.; Sidis, V.; Barat, M.; Pollack, Edward

doi:10.1103/physreva.11.1245

Cited by 139 publications

(50 citation statements)

References 40 publications

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“…2,5,22 All the crossing features deduced with the model for symmetric and quasisymmetric systems coincide with those by the MO and energy correlation diagrams. 11 Figure 3 exhibits the difference potentials for the asymmetric Li ϩ -Ne and largely asymmetric Li ϩ -Ar calculated with the overlap model in the same way as for the Na ϩ -Ne.…”

Section: Ne-ne Interactionssupporting

confidence: 73%

“…The distance R c ϭ0.90 Å agrees well with the theoretical and experimental R c ϭ0.94 Å (Vϭ48 eV). 2,22 These potential crossings of curves 2 and 3 with curve 1 are considered to originate from the MO crossing between 4 f u and 3s g . In order to explain fully the differential scattering experiments for Ne-Ne, one has to take into account the MO 4 f u Ϫ4p u and 4 f u Ϫ5 p u crossings, 23 because for excitation of a Ne atom into the 3s state there is no interaction between the 4 f u and 3s g MO's with a different symmetry.…”

Section: Ne-ne Interactionsmentioning

confidence: 99%

“…It will be meaningful to compare the R c ϭ0.90 Å for Ne-Ne with the theoretical R c ϭ0.87 Å for Ne ϩ -Ne due to the MO 4 f u Ϫ3s g crossing. 2 The MO crossing for Ne ϩ -Ne is the same as that for Ne-Ne. Curve 4 in the figure, which is for excitation of a Ne atom into the autoionizing Ne͓2 p 4 ( 1 D)3s 2 ͔ state with Q 2e (2)ϭ45 eV, crosses curve 1 at R c ϭ0.81 Å (Vϭ100 eV) and curve 2 at R c ϭ0.76 Å (Vϭ120 eV).…”

Section: Ne-ne Interactionsmentioning

confidence: 99%

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Charge-overlap effect on the electronic transitions in moderate-energy collisions between closed-shell particles with rare-gas structure

Kita

Gotoh

Hasegawa

et al. 1998

The Journal of Chemical Physics

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A combining rule calculation of the ground state van der Waals potentials of the mercury rare-gas complexes Electronic excitation and charge transfer processes in collisions between Mg (3 1 S 0 ) atoms and Rb + ( 1 S 0 ) ions in the 0.07-4.00 keV energy range A potential model, which is represented by the overlap of electron clouds of interacting particles, has been applied to discuss the diabatic potential crossings which lead to one-and two-electron transitions in moderate-energy collisions of closed-shell particles. The crossings evaluated with the potential model interpret reasonably well both differential scattering experiments and ab initio calculations. In the model, the potential crossings originate from the hole͑s͒ produced by the promotion of electron͑s͒ in the outermost shell͑s͒ of incident particle͑s͒.

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Section: Ne-ne Interactionssupporting

confidence: 73%

Section: Ne-ne Interactionsmentioning

confidence: 99%

Section: Ne-ne Interactionsmentioning

confidence: 99%

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Charge-overlap effect on the electronic transitions in moderate-energy collisions between closed-shell particles with rare-gas structure

Kita

Gotoh

Hasegawa

et al. 1998

The Journal of Chemical Physics

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“…The effect observed in our studies supports this interpretation. One of the possible mechanisms of such an Auger process is a binary type quasimolecular or "Diabatic II" Auger transition [17]. Electronic states involved in this transition correspond to the molecular orbitals of the Ne 1 ͞F 2 system which are strongly splitted by the interaction [18].…”

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confidence: 99%

Evidence for the Stopping of Slow Ions by Excitations of Optical Phonons in Insulators

et al. 1999

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The energy loss of Ne 1 ions with keV energies scattered under grazing incidence from a LiF(001) surface is studied with a time-of-flight technique. Since charge exchange in front of the wide-bandgap insulator is widely suppressed, the energy loss of slow ions moving in front of the solid can be investigated under specific interaction conditions. From the theoretical analysis of data we find evidence for an energy loss mechanism based on the excitations of optical phonons in the insulator. PACS numbers: 79.20.Rf, 34.50.Bw When atomic particles collide with solid matter, excitations in projectile and target give rise to stopping phenomena. For slow ions electronic excitations, charge exchange, and binary collisions with target atoms ("nuclear stopping") clearly dominate the dissipation of energy in ion-solid collisions [1]. Whereas nuclear stopping can be described in a straightforward manner, the treatment of electronic processes is a more intricate subject. For metal targets, considerable progress in the theoretical description of electronic stopping has been achieved over about the last decade [2]. Excitation of electron-hole pairs is the primary mechanism for electronic stopping of slow ions, i.e., projectiles with velocities y ø y 0 (y 0 Bohr velocity 1 atomic unit 1 a.u.). In the framework of corresponding theories, characteristic features for the stopping of slow ions by metal targets, e.g., a linear dependence of the stopping power 2dE͞dx on the projectile velocity y or oscillations of 2dE͞dx with atomic number of the projectiles Z 1 ("Z 1 oscillations"), can be described on a quantitative level [3].An interesting aspect concerning the stopping of slow ions is the role of collective excitations. Whereas at higher projectile velocities excitations of plasmons (typical energieshv ഠ 10 eV) result in substantial contributions to energy loss [2,4], these excitations will have small effects on the stopping of slow ions [5]. From a theoretical analysis Echenique and Howie [6] concluded that at low velocities only collective excitations at low frequencies, as, e.g., optical phonons in ionic insulators (typical energieshv ph ഠ some 10 meV [7]) will contribute. In order to observe this mode of stopping, other sources for dissipation of energy of slow ions (single excitations, charge exchange, nuclear stopping) has to be reduced. To our knowledge, corresponding experimental work has not been reported so far.In this Letter, we report on joint experimental and theoretical studies where unequivocal evidence for the stopping of slow ions in front of an ionic insulator by excitation of optical phonons is obtained. We will demonstrate that under specific experimental conditions for collisions of ions with solid matter, the excitations of phonons clearly dominate the stopping process. Our experiments are performed with Ne 1 ions at keV energies ͑y # 0.1 a.u.͒ scattered under grazing angles of incidence (typically F in ഠ 1 ± ) from a clean and flat LiF(001) surface. Under these scattering conditions ("planar surface chann...

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“…Non-elastic scattering channels available for collision spectroscopy methods (ionization, excitation of resonance and metastable states [1][2][3]) for the system He( 1 S 0 ) +He( 1 S 0 ) were investigated most thoroughly. The excitation cross sections of some states He(1snl ) with n = 2 .…”

Section: Introductionmentioning

confidence: 99%

On mechanisms of He I collisional excitation in He-He system

Kurskov

Khakhaev

2006

Czech J Phys

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The present work is devoted to study of He I excitation in low energy He-He collisions. The purpose of this work is the investigation of mechanisms of atomic levels excitation at collision energies, corresponding the conditions of adiabatic approximation. The results of the experimental investigation of the excitation cross sections of He I 3 1 P, 3 3 P, 3 1 D, 3 3 D levels in the collision energy range from threshold up to 500 eV (c.m. system) and degree of polarization for 2 1 S-3 1 P, 2 3 S-3 3 P, 2 1 P-3 1 D and 2 3 P-3 3 D transitions in this energy range are represented. Also the degree of polarization for 2 1 P-n 1 D transitions as function of the main quantum number (3 ≤ n ≤ 12) at the fixed collision energy is represented.PACS : 34.50.Fa

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Collisions between rare-gas atoms at low keV energies. I. Symmetric systems

Cited by 139 publications

References 40 publications

Charge-overlap effect on the electronic transitions in moderate-energy collisions between closed-shell particles with rare-gas structure

Charge-overlap effect on the electronic transitions in moderate-energy collisions between closed-shell particles with rare-gas structure

Evidence for the Stopping of Slow Ions by Excitations of Optical Phonons in Insulators

On mechanisms of He I collisional excitation in He-He system

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