Charge exchange of He+-ions with aluminium surfaces

Rund, S.; Primetzhofer, Daniel; Markin, S.N.; Goebl, D.; Bauer, Péter

doi:10.1016/j.nimb.2010.11.049

Cited by 22 publications

(15 citation statements)

References 14 publications

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“…At an interaction distance of 0.75 a.u., He 1s is known to be shifted above the Fermi level E F of Al [38,39]. This leads to very effective neutralization of He þ ions within 1-2 monolayers [40]. The same promotion mechanism also enables ionization of He atoms: at sufficiently close distance neutral He can lose an electron and thus become (re)ionized.…”

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confidence: 99%

Electronic Excitations of Slow Ions in a Free Electron Gas Metal: Evidence for Charge Exchange Effects

et al. 2011

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Electronic energy loss of light ions transmitted through nanometer films of Al has been studied at very low ion velocities. For hydrogen, the electronic stopping power S is found to be perfectly proportional to velocity, as expected for a free electron gas. For He, the same is anticipated, but S shows a transition between two distinct regimes, in both of which S is velocity proportional-however, with remarkably different slopes. This finding can be explained as a consequence of charge exchange in close encounters between He and Al atoms, which represents an additional energy loss channel.

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confidence: 99%

Electronic Excitations of Slow Ions in a Free Electron Gas Metal: Evidence for Charge Exchange Effects

et al. 2011

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“…the maximum intensity of backscattered projectiles, typically is found at a lower energy than kE0 due to interactions of the projectile with the target electrons causing a deceleration of the projectile (electronic stopping). The asymmetric shape of the Al peak is mainly due to contributions of re-ionized projectiles scattered from the surface [15]. Projectiles scattered from deeper layers, which are re-ionized on the exit trajectory, result in a continuous background for Eth < E < kE0.…”

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confidence: 99%

“…3, the peak can be fitted with two Gaussians under consideration of the background (dash-dotted line). The peak position of the two Gaussians differs by ~ 20 eV, representing contributions from either projectiles surviving AN (black dashed line) or from re-ionized projectiles (black dotted line), both scattered from the surface [15]. If the distance between the two peaks were larger than their combined FWHM, information on both Auger neutralization and re-ionization efficiency could be straightforward deduced.…”

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confidence: 99%

Neutralization of slow helium ions scattered from single crystalline aluminum and tantalum surfaces and their oxides

2020

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We investigated the impact of surface oxygen on the ion yield for He + ions scattered from different single crystalline surfaces in low-energy ion scattering. Initially clean Al(111) and Ta(111) were exposed to molecular oxygen and ion spectra for different oxidation stages and different primary energies were recorded. A comparison of ion yields normalized to the differential scattering cross section as well as experimental factors allows obtaining information about the influence of oxygen on charge exchange processes. The decrease in the ion yield of both metals with exposure cannot be explained by different surface coverages exclusively, but requires the neutralization efficiency to be dependent on the chemical structure of the surface. For Ta, additionally, a different energy dependency of the ion yield obtained in the metal and oxide occurs. The ion yield for O shows in both surfaces a significantly weaker energy dependency than the investigated metals.

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“…5f. For both projectiles, we observed alternate neutralization and re-ionization processes along their trajectories [51,71]. These differences in the electronic charge of the projectiles in Fig.…”

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confidence: 91%

Directional dependency of electronic stopping in nickel, projectile’s excited charge state and momentum transfer

2021

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We studied the directional dependency of electronic stopping power of swift light ions in nickel using real-time time-dependent density functional theory. We report a variation of electronic stopping for moving ions as the projectile probes different electronic densities of the host material. These results show that while the predicted magnitude stays in reasonable agreement with experiment, for $$v > 2$$ v > 2 . a.u. simulating only low index crystallographic directions is not enough to sample the experimental average values. The ab initio simulations give us access to microscopic quantities, such as non-adiabatic forces, momentum transfer and transient excited state charges of the projectile and host ions, which are not available through other methods. We report these quantities for the first time.

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Charge exchange of He+-ions with aluminium surfaces

Cited by 22 publications

References 14 publications

Electronic Excitations of Slow Ions in a Free Electron Gas Metal: Evidence for Charge Exchange Effects

Electronic Excitations of Slow Ions in a Free Electron Gas Metal: Evidence for Charge Exchange Effects

Neutralization of slow helium ions scattered from single crystalline aluminum and tantalum surfaces and their oxides

Directional dependency of electronic stopping in nickel, projectile’s excited charge state and momentum transfer

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