Computational study of low energy ion surface hyperchanneling

Fang, Zhaoxi; Lau, Woon Ming; Rabalais, J. W.

doi:10.1016/j.susc.2005.01.057

Cited by 10 publications

(3 citation statements)

References 20 publications

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“…Therefore, for charge transfer of keV-ion/atom surface scattering under a small grazing angle of incidence, i.e., 1°, the scattering event occurs above the surface because the incident angle is smaller than the related critical angle. It is easy to understand that projectiles have a large probability to penetrate into the surface when the incident angle is larger than the critical angle. − For scattering on a HOPG (0001) surface [ n s = 3.845 × 10 15 atom/cm 2 ], we find the critical angle is from about 5.18° to 8.88° for C – energies from 22.5 to 8.5 keV. For O – with the same energies, it is about 5.83° to 10.00°, and for F – ions, it is about 6.12° to 10.49°.…”

Section: Discussionmentioning

confidence: 85%

Anomalous Positive Ion Formation in Negative Ion Collisions with HOPG

et al. 2016

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Charge transfer on graphite, a typical substrate and one of the fusion first wall materials, is of great importance in the plasma–wall interaction, thin-film growth, and surface catalysis. We present an experimental study of 8.5–22.5 keV energy carbon, oxygen, and fluorine negative ions scattering from a highly oriented pyrolytic graphite (HOPG) surface at a scattering angle of 8°. It is found that the positive ion fraction decreases monotonically with the increase of both incident velocity and angle. In particular, these dependences are very different from those presented in previous studies. A molecular dynamics simulation reveals that, around the critical condition for planar surface channeling, a number of projectiles may penetrate into the subsurface and become energetic atoms when they emerge from the surface. Hence, an exponential scaling related to the penetration probability has been proposed to well describe the velocity and angle dependences of positive ion fractions.

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Section: Discussionmentioning

confidence: 85%

Anomalous Positive Ion Formation in Negative Ion Collisions with HOPG

et al. 2016

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“…In 2002, S. M. Hogg et al [24] studied channeled implantation of 80 keV Er ions into Si and concluded that the axial measured critical angle was in excellent agreement with both computer simulations (made with the MDRANGE program [17]) and experimental results. In 2005 Lindhard's critical angle prediction was used to understand qualitative features of computational results of the SARIC program for 4 keV Ne + ions impinging on a Pt surface [25].…”

Section: Continuum Modelsmentioning

confidence: 99%

Channeling in direct dark matter detection I: channeling fraction in NaI (Tl) crystals

Bozorgnia¹,

Gelmini²,

Gondolo

2010

J. Cosmol. Astropart. Phys.

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The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in NaI (Tl) crystals using analytic models produced since the 1960's and 70's to describe channeling and blocking effects. We find that the channeling fraction of recoiling lattice nuclei is smaller than that of ions that are injected into the crystal and that it is strongly temperature dependent.

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“…Experiments using also Ne + projectiles were performed to study inelastic energy loss in scattering of ions from a Si surface [11]. From a theoretical point of view, model potential energy surfaces and classical methods have been recently developed and employed to study scattering at grazing incidence of He + , Ne + , and Ar + from Pt(111)-(1×1) [15] and Si(100) [16]. Scattering of molecular ionic beams (H 2 + and D 2 + ) has also been studied, both theoretically and experimentally.…”

Section: Introductionmentioning

confidence: 99%

Reactive scattering ofH2from metal surfaces under fast-grazing-incidence conditions

Dı́az

Martín

2010

Phys. Rev. A

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We have studied the interaction of molecular hydrogen with metal surfaces under fast-grazing-incidence conditions, by means of classical dynamics calculations based on density functional theory six-dimensional potential energy surfaces. We have performed calculations on two activated systems, H 2 /NiAl(110) and H 2 /Cu(111), and on two nonactivated systems, H 2 /Pd(111) and H 2 /Pd(110). We show that for rather open surfaces the computed 1 − R probabilities (where R represents the reflectivity) as a function of the normal collision energy at grazing incidence (along low-Miller-index directions) mimic reasonably well the dissociative adsorption probabilities obtained at normal incidence and thermal energies from the dissociation threshold up to the saturation limit. Our results indicate that fast grazing incidence experiments could be used as complement to traditional sticking experiments at thermal energies to determine dissociative adsorption saturation limits, which are usually unreachable due to limitations in traditional molecular beam experiments

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Computational study of low energy ion surface hyperchanneling

Cited by 10 publications

References 20 publications

Anomalous Positive Ion Formation in Negative Ion Collisions with HOPG

Anomalous Positive Ion Formation in Negative Ion Collisions with HOPG

Channeling in direct dark matter detection I: channeling fraction in NaI (Tl) crystals

Reactive scattering ofH2from metal surfaces under fast-grazing-incidence conditions

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