Charge State Dependence of the Energy Loss of Slow Ions in Metals

Juaristi, J. I.; Arnau, A.; Echenique, Pedro M.; Auth, C.; Winter, H.

doi:10.1103/physrevlett.82.1048

Cited by 81 publications

(34 citation statements)

References 21 publications

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“…[11], the Transport Cross Section (TCS) calculations presented in Ref. [10], or the more elaborate Density Functional Theory (DFT) could be used [9,38]. However, these models also have constraints.…”

Section: Stopping Power and Energy Loss Straggling Associated To Captmentioning

confidence: 99%

Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets

Denton

Abril

Moreno-Marı́n

et al. 2008

Physica Status Solidi (b)

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We have calculated the stopping power of Al, Si, Ni and Cu for swift H and He ion beams. Furthermore, the energy loss straggling corresponding to Ni is also evaluated. The dielectric formalism is used combined with the MELF‐GOS method, which describes the energy loss function of the target by a linear combination of Mermin type energy loss functions for the electron outer‐shell electrons and by generalized oscillator strengths for the electron inner‐shell electrons. We take into account the corrections to the stopping power associated to capture and loss of electrons by the projectile as well as the polarization of the projectile charge density. The versatility of this method is illustrated by the good agreement between their predictions and the experimental results, which is observed for a wide range of projectile energies and targets with different electronic properties. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Stopping Power and Energy Loss Straggling Associated To Captmentioning

confidence: 99%

Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets

Denton

Abril

Moreno-Marı́n

et al. 2008

Physica Status Solidi (b)

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“…The friction coefficient so calculated has been widely and successfully used in the context of the stopping power of atoms and ions in the bulk [24,25] and surface regions [26]. For H atoms penetrating several layers of Al, the TDDFT calculation of Ref.…”

mentioning

confidence: 99%

Role of Electron-Hole Pair Excitations in the Dissociative Adsorption of Diatomic Molecules on Metal Surfaces

et al. 2008

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We quantitatively evaluate the contribution of electron-hole pair excitations to the reactive dynamics of H 2 on Cu(110) and N 2 on W(110), including the six dimensionality of the process in the entire calculation. The interaction energy between molecule and surface is represented by an ab initio six-dimensional potential energy surface. Electron friction coefficients are calculated with density functional theory in a local density approximation. Contrary to previous claims, only minor differences between the adiabatic and nonadiabatic results for dissociative adsorption are found. Our calculations demonstrate the validity of the adiabatic approximation to analyze adsorption dynamics in these two representative systems. DOI: 10.1103/PhysRevLett.100.116102 PACS numbers: 82.65.+r, 34.35.+a, 68.49.Df, 82.20.Kh The adiabatic Born-Oppenheimer approximation is ubiquitous in the theoretical study of elementary reactive processes at surfaces. Still, there is ample experimental evidence of electronic excitations associated to gas or surface reactions, that can potentially break down the applicability of the adiabatic approach. Electron-hole pairs appear, for instance, in the detection of chemicurrents during the chemisorption of gas-phase species on thin metal films [1,2], as well as in the measurement of electron emission following the scattering of molecules in highlyexcited vibrational states on metal surfaces [3,4]. Although the existence of energy dissipation through electron-hole (e-h) pair excitations is widely accepted, there is not a definite quantitative answer on the role of electronic excitations in the adsorption and reaction rates of diatomic molecules at metal surfaces [5].Laursen et al. [6] predicted that e-h pair excitations should alter substantially the adsorption dynamics of H 2 in Cu (110). Contravening this prediction, full sixdimensional (6D) adiabatic calculations of the dynamics based on an ab initio potential energy surface have been shown to provide a good description of the experimental results on this system [7]. Measurements of the dissociative adsorption and diffractive scattering of H 2 on Pt(111) are reasonably well described within the adiabatic approximation as well [8]. For heavier molecules, it was claimed that strong energy dissipation effects due to the excitation of e-h pairs are responsible for the strong disagreement between (adiabatic) theoretical and experimental sticking coefficients for N 2 on Ru(0001) [9,10]. Díaz et al. [11] showed afterwards that when the full dimensionality of the process is taken into account, adiabatic calculations are much closer to experiments. This result suggests that nonadiabatic effects might be smaller than previously predicted. Still, the lack of a theoretical calculation, based on state-of-the-art interaction potentials, that explicitly includes the e-h pair excitation channel and the full dimensionality of the process keeps this controversy open.In this Letter, we evaluate the contribution of e-h pair excitations to the dissociative adsorp...

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“…Friction coefficients computed within the LDFA have previously been successfully applied to understand different properties of the energy loss of atoms and ions on surfaces. [93][94][95][96] Here, an additional approximation made was that the electronic density was calculated fixing the metal atoms at their equilibrium positions at T s = 120 K.…”

Section: Ab Initio Molecular Dynamics With Electronic Friction Calmentioning

confidence: 99%

Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111)

Kroes

Pavanello

Blanco-Rey

et al. 2014

The Journal of Chemical Physics

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In-plane structure and ordering at liquid sodium surfaces and interfaces from ab initio molecular dynamics J. Chem. Phys. 127, 134703 (2007); 10.1063/1.2781388Publisher's Note: "Ab initio molecular dynamics simulation of the H/InP(100)-water interface" [J. Chem. Phys. 117, 872 (2002) Energy loss from the translational motion of an atom or molecule impinging on a metal surface to the surface may determine whether the incident particle can trap on the surface, and whether it has enough energy left to react with another molecule present at the surface. Although this is relevant to heterogeneous catalysis, the relative extent to which energy loss of hot atoms takes place to phonons or electron-hole pair (ehp) excitation, and its dependence on the system's parameters, remain largely unknown. We address these questions for two systems that present an extreme case of the mass ratio of the incident atom to the surface atom, i.e., H + Cu(111) and H + Au(111), by presenting adiabatic ab initio molecular dynamics (AIMD) predictions of the energy loss and angular distributions for an incidence energy of 5 eV. The results are compared to the results of AIMDEFp calculations modeling energy loss to ehp excitation using an electronic friction ("EF") model applied to the AIMD trajectories, so that the energy loss to the electrons is calculated "post" ("p") the computation of the AIMD trajectory. The AIMD calculations predict average energy losses of 0.38 eV for Cu(111) and 0.13-0.14 eV for Au(111) for H-atoms that scatter from these surfaces without penetrating the surface. These energies closely correspond with energy losses predicted with Baule models, which is suggestive of structure scattering. The predicted adiabatic integral energy loss spectra (integrated over all final scattering angles) all display a lowest energy peak at an energy corresponding to approximately 80% of the average adiabatic energy loss for non-penetrative scattering. In the adiabatic limit, this suggests a way of determining the approximate average energy loss of non-penetratively scattered H-atoms from the integral energy loss spectrum of all scattered H-atoms. The AIMDEFp calculations predict that in each case the lowest energy loss peak should show additional energy loss in the range 0.2-0.3 eV due to ehp excitation, which should be possible to observe. The average non-adiabatic energy losses for non-penetrative scattering exceed the adiabatic losses to phonons by 0.9-1.0 eV. This suggests that for scattering of hyperthermal H-atoms from coinage metals the dominant energy dissipation channel should be to ehp excitation. These predictions can be tested by experiments that combine techniques for generating H-atom beams that are well resolved in translational energy and for detecting the scattered atoms with high energy-resolution. © 2014 AIP Publishing LLC.

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Charge State Dependence of the Energy Loss of Slow Ions in Metals

Cited by 81 publications

References 21 publications

Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets

Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets

Role of Electron-Hole Pair Excitations in the Dissociative Adsorption of Diatomic Molecules on Metal Surfaces

Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111)

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