Electronic excitation in metals through hyperthermal atoms

Kovacs, Domocos; Babkina, T. V.; Gans, Timo; Czarnetzki, Uwe; Diesing, Detlef

doi:10.1088/0022-3727/39/24/019

Cited by 12 publications

(8 citation statements)

References 37 publications

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“…Even if the bombarding energy is reduced further ͑down to about 200 eV͒, the monotonic dependence of ␥ t is found to continue, and the potential contribution to the measured tunneling yield can thus be estimated to be on the order of 10 −3 or below. 28 The reason for the discrepancy between the data displayed in Fig. 4 and those of Ref.…”

Section: B Kinetic-energy Dependencementioning

confidence: 73%

Kinetic electronic excitation of solids by fast-particle bombardment

et al. 2008

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The kinetic excitation of hot electrons and conduction-band vacancies following the impact of an energetic particle onto a solid surface was studied using metal-insulator-metal tunnel junctions. The top metal layer ͑polycrystalline silver͒ was bombarded by charged and neutral Ar projectiles of kinetic energies between 1 and 15 keV. Hot charge carriers generated within the collision cascade initiated by the projectile impact were detected as a tunneling current across the oxide barrier into the underlying substrate metal electrode. The tunneling yield is shown to depend monotonously on the kinetic impact energy with no notable contribution of potential emission. The dependence, however, is different for singly charged and neutral projectiles. Applying a bias voltage between the two metal electrodes, information about the energy spectrum of the excited carriers is obtained. The experimental data are interpreted in terms of a simple two-temperature tunneling model, yielding a kinetically induced transient electron "temperature" on the order of 10 4 K.

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Section: B Kinetic-energy Dependencementioning

confidence: 73%

Kinetic electronic excitation of solids by fast-particle bombardment

et al. 2008

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“…Energetic neutrals produced through neutralization of energetic ions at surfaces can also contribute to neutral gas heating. Details of the energy balance during this neutralization process depend critically on the mass ratio of the impinging ions and the surface material [18][19][20]. In our case, with argon ions and stainless steel chamber walls, the influence on neutral gas heating can be expected to be small in comparison with charge transfer collisions.…”

Section: Resultsmentioning

confidence: 93%

Neutral gas depletion mechanisms in dense low-temperature argon plasmas

O’Connell¹,

Gans²,

Crintea³

et al. 2008

J. Phys. D: Appl. Phys.

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Neutral gas depletion mechanisms are investigated in a dense low-temperature argon plasma—an inductively coupled magnetic neutral loop (NL) discharge. Gas temperatures are deduced from the Doppler profile of the 772.38 nm line absorbed by argon metastable atoms. Electron density and temperature measurements reveal that at pressures below 0.1 Pa, relatively high degrees of ionization (exceeding 1%) result in electron pressures, pe = kTene, exceeding the neutral gas pressure. In this regime, neutral dynamics has to be taken into account and depletion through comparatively high ionization rates becomes important. This additional depletion mechanism can be spatially separated due to non-uniform electron temperature and density profiles (non-uniform ionization rate), while the gas temperature is rather uniform within the discharge region. Spatial profiles of the depletion of metastable argon atoms in the NL region are observed by laser induced fluorescence spectroscopy. In this region, the depletion of ground state argon atoms is expected to be even more pronounced since in the investigated high electron density regime the ratio of metastable and ground state argon atom densities is governed by the electron temperature, which peaks in the NL region. This neutral gas depletion is attributed to a high ionization rate in the NL zone and fast ion loss through ambipolar diffusion along the magnetic field lines. This is totally different from what is observed at pressures above 10 Pa where the degree of ionization is relatively low (<10−3) and neutral gas depletion is dominated by gas heating.

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“…The energy dissipation is caused by the carrier excitation, besides the phonon. The former results in the electronic emission from the surface whose yield is dependent on the energy transfer [29][30][31] .…”

Section: Theoretical Modelmentioning

confidence: 99%

“…The absolute yield of the carrier excitation per projectile particle ( Y ) is defined as the ratio of the carrier generation rate ( G ) to the incident particle flux F. Y increases with respect to the increment of the energy transfer E Δ during the collision [30,31] , which can be expressed as ,…”

Section: Dependence Of Translational Kinetic Energymentioning

confidence: 99%

A reaction-diffusion model for atomic oxygen interacting with spacecraft surface protective materials in low earth orbit environment

Chen

Wang

Lee

2009

Sci. China Ser. E-Technol. Sci.

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When hyperthermal atomic oxygen collides with a silicon surface, an ultrathin oxidation regime characterized by fractional atomic-oxygen anions having low diffusive and reactive barriers, along with their enhanced diffusion due to both the electric field and image potential, will form on the surface. In accordance with these properties, an attempt was made in the present study to modify the AlmeidaGoncalves-Baumvol (AGB) model by setting the diffusivity and reaction rate constant to be diffusion-length dependence. According to the modified model, numerical parametric studies for oxidation thin growth were performed. The dependencies of the diffusion coefficient, the reaction rate constant, the attenuation length, and the adjustable parameter upon the translational kinetic energy, flux, temperature, and tangential flux of atomic oxygen were analyzed briefly via the fitting of the experimental data given by Tagawa et al. The numerical results confirmed the rationality of the modified diffusion-reaction model. The model together with the computer code developed in this study would be a useful tool for thickness evaluation of the protective film against the oxidation of atomic oxygen toward spacecraft surface materials in LEO environment.hyperthermal atomic oxygen,

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Electronic excitation in metals through hyperthermal atoms

Cited by 12 publications

References 37 publications

Kinetic electronic excitation of solids by fast-particle bombardment

Kinetic electronic excitation of solids by fast-particle bombardment

Neutral gas depletion mechanisms in dense low-temperature argon plasmas

A reaction-diffusion model for atomic oxygen interacting with spacecraft surface protective materials in low earth orbit environment

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