References of "Lemell, C"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailCollisions of slow highly charged ions with surfaces
Burgdoerfer, J.; Lemell, C.; Schiessl, K. et al

in Fainstein, P.D.; Lima, M.A.P.; Miraglia, J.E. (Eds.) et al Photonic, Electronic and Atomic Collisions, Proceedings of the XXIV International Conference (2006)

Progress in the study of collisions of multiply charged ions with surfaces is reviewed with the help of a few recent examples. They range from fundamental quasi-one electron processes to highly complex ... [more ▼]

Progress in the study of collisions of multiply charged ions with surfaces is reviewed with the help of a few recent examples. They range from fundamental quasi-one electron processes to highly complex ablation and material modification processes. Open questions and possible future directions will be discussed. [less ▲]

Detailed reference viewed: 56 (1 UL)
Peer Reviewed
See detailElectron emission from surfaces induced by HCI and lasers
Lemell, C.; Tong, X. M.; Tokesi, K. et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2005), 235

Electron emission from surfaces due to interaction with charged particles and electromagnetic fields is a topic of research for over 100 years. In the past decade new developments in the production of ... [more ▼]

Electron emission from surfaces due to interaction with charged particles and electromagnetic fields is a topic of research for over 100 years. In the past decade new developments in the production of ultrashort laser pulses (tau < 10 fs at a wavelength of lambda approximate to 750 nm) and of slow highly charged ions (HCI) have rendered these interactions to be remarkably similar. The description of electron emission in HO-surface interactions can therefore be transcribed to model and understand photoemission from surfaces interacting with ultrashort laser pulses. Examples will be presented for two model systems. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 48 (0 UL)
Full Text
Peer Reviewed
See detailMulti-electron dynamics for neutralization of highly charged ions near surfaces
Burgdorfer, J.; Wirtz, Ludger UL; Reinhold, C. O. et al

in Vacuum (2004), 73(1), 3-7

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte ... [more ▼]

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte-Carlo solution of the Liouville master equation for the joint probability density of the ionic motion and the electronic population of the projectile and the target surface. It includes single as well as double particle-hole (de)excitation processes and incorporates electron correlation effects through the conditional dynamics of population strings. For slow projectiles and normal incidence, the ionic motion depends sensitively on the interplay between image acceleration towards the surface and repulsion by an ensemble of positive hole charges in the surface ("trampoline effect"). For Ne10+ we find that image acceleration is dominant and no collective backscattering high above the surface takes place. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 40 (0 UL)
Full Text
Peer Reviewed
See detailAngular distribution of highly charged ions transmitted through metallic microcapillaries
Tokesi, K.; Wirtz, Ludger UL; Lemell, C. et al

in Journal of Electron Spectroscopy & Related Phenomena (2003), 129(2-3), 195-200

The angular distribution of Xe6+ ions with an energy of 800 eV/q transmitted through Ni microcapillaries is studied by a classical trajectory simulation. The results for clean and contaminated by layers ... [more ▼]

The angular distribution of Xe6+ ions with an energy of 800 eV/q transmitted through Ni microcapillaries is studied by a classical trajectory simulation. The results for clean and contaminated by layers of insulating materials of the internal surface of capillary are presented. We show that the angular distributions can be used to identify different phases of hollow ion formation for clean metal surface. We also show that the angular distribution changes dramatically for the case of contaminated surface, i.e. when the image acceleration is depressed. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 38 (0 UL)
Full Text
Peer Reviewed
See detailLiouville master equation for multielectron dynamics: Neutralization of highly charged ions near a LiF surface
Wirtz, Ludger UL; Reinhold, C. O.; Lemell, C. et al

in Physical Review. A (2003), 67(1),

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte ... [more ▼]

We present a simulation of the neutralization of highly charged ions in front of a lithium fluoride surface including the close-collision regime above the surface. The present approach employs a Monte Carlo solution of the Liouville master equation for the joint probability density of the ionic motion and the electronic population of the projectile and the target surface. It includes single as well as double particle-hole (de)excitation processes and incorporates electron correlation effects through the conditional dynamics of population strings. The input in terms of elementary one- and two-electron transfer rates is determined from classical trajectory Monte Carlo calculations as well as quantum-mechanical Auger calculations. For slow projectiles and normal incidence, the ionic motion depends sensitively on the interplay between image acceleration towards the surface and repulsion by an ensemble of positive hole charges in the surface ("trampoline effect"). For Ne10+ we find that image acceleration is dominant and no collective backscattering high above the surface takes place. For grazing incidence, our simulation delineates the pathways to complete neutralization. In accordance with recent experimental observations, most ions are reflected as neutral or even as singly charged negative particles, irrespective of the charge state of the incoming ions. [less ▲]

Detailed reference viewed: 88 (0 UL)
Full Text
Peer Reviewed
See detailKinetically assisted potential sputtering of insulators by highly charged ions
Hayderer, G.; Cernusca, S.; Schmid, M. et al

in Physical Review Letters (2001), 86(16), 3530-3533

A new form of potential sputtering has been found for impact of slow (less than or equal to 1500 eV) multiply charged Xe ions (charge states up to q = 25) on MgOx. In contrast to alkali-halide or SiO2 ... [more ▼]

A new form of potential sputtering has been found for impact of slow (less than or equal to 1500 eV) multiply charged Xe ions (charge states up to q = 25) on MgOx. In contrast to alkali-halide or SiO2 surfaces this mechanism requires the simultaneous presence of electronic excitation of the target material and of a kinetically formed collision cascade within the target in order to initiate the sputtering process. This kinetically assisted potential sputtering mechanism has been identified to be present for ether insulating surfaces as well. [less ▲]

Detailed reference viewed: 50 (0 UL)
Full Text
Peer Reviewed
See detailHollow-ion formation in microcapillaries
Tokesi, K.; Wirtz, Ludger UL; Lemell, C. et al

in Physical Review. A (2001), 64(4),

Transmission of highly charged ions through microcapillaries is studied theoretically by a classical trajectory simulation. The interaction of highly charged ions with the internal surface of the ... [more ▼]

Transmission of highly charged ions through microcapillaries is studied theoretically by a classical trajectory simulation. The interaction of highly charged ions with the internal surface of the capillary is treated within the framework of dielectric-response theory. The simulation is based on the classical over-the-barrier model modified for open cylindrical surfaces. The multielectron evolution and relaxation is taken into account as a stochastic event sequence. We consider N6+ and Ne10+ with an energy of 2.1 keV/amu passing through a metallic microcapillary of Ni. We analyze the distance of closest approach. the angular distribution, and the distribution of the mean occupation numbers of n shells of highly charged ions. We find the resulting charge state distribution of transmitted projectiles in good agreement with recent measurements. Implications for nanotube targets will be discussed. [less ▲]

Detailed reference viewed: 49 (0 UL)
Peer Reviewed
See detailScattering of highly charged ions at microcapillaries
Tokesi, K.; Wirtz, Ludger UL; Lemell, C. et al

Scientific Conference (2001)

Transmission of highly charged ions through microcapillaries is studied theoretically by a classical trajectory simulation based on the classical-over-the-barrier model. The interaction of highly charged ... [more ▼]

Transmission of highly charged ions through microcapillaries is studied theoretically by a classical trajectory simulation based on the classical-over-the-barrier model. The interaction of highly charged ions with the internal surface of the capillary is treated within the framework of dielectric response theory. We find the resulting charge state distribution of transmitted projectiles in good agreement with measurements. We analyze the angular distributions and the distribution of the mean occupation numbers of n shells of highly charged ions. We also present theoretical results of the energy loss of the highly charged ions undergoing distant collisions at grazing incidence angles with the internal surface of the microcapillary target. [less ▲]

Detailed reference viewed: 33 (0 UL)
Full Text
Peer Reviewed
See detailVertical incidence of slow Ne10+ ions on an LiF surface: Suppression of the trampoline effect
Wirtz, Ludger UL; Lemell, C.; Reinhold, C. O. et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2001), 182

We present a Monte Carlo simulation of the neutralization of a slow Ne10+ ion in vertical incidence on an LiF(100) surface. The rates for resonant electron transfer between surface F- ions and the ... [more ▼]

We present a Monte Carlo simulation of the neutralization of a slow Ne10+ ion in vertical incidence on an LiF(100) surface. The rates for resonant electron transfer between surface F- ions and the projectile are calculated using a classical trajectory Monte Carlo simulation, We investigate the influence of the hole mobility on the neutralization sequence. It is shown that backscattering above the surface due to the local positive charge up of the surface ("trampoline effect") does not take place. (C) 2001 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 50 (0 UL)
Full Text
Peer Reviewed
See detailCurve-crossing analysis for potential sputtering of insulators
Wirtz, Ludger UL; Hayderer, G.; Lemell, C. et al

in Surface Science (2000), 451(1-3), 197-202

We develop a theoretical model for the recently observed threshold for potential sputtering of LiF by slow singly and doubly charged ions. The threshold coincides with the potential energy to create a ... [more ▼]

We develop a theoretical model for the recently observed threshold for potential sputtering of LiF by slow singly and doubly charged ions. The threshold coincides with the potential energy to create a cold hole in the valence band of LiF by resonant neutralization. We calculate the level shift of the incident ion and the deformation of the valence band under the influence of the projectile. Resonant neutralization becomes possible for ions with recombination energies larger than 10 eV in agreement with the experimental findings. (C) 2000 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 43 (0 UL)
Full Text
Peer Reviewed
See detailCharge-state evolution of highly charged ions transmitted through microcapillaries
Tokesi, K.; Wirtz, Ludger UL; Lemell, C. et al

in Physical Review. A (2000), 61(2),

The charge-state evolution of highly charged ions transmitted through microcapillaries is studied theoretically by a classical trajectory Monte Carlo simulation.: The interaction of highly charged ions ... [more ▼]

The charge-state evolution of highly charged ions transmitted through microcapillaries is studied theoretically by a classical trajectory Monte Carlo simulation.: The interaction of highly charged ions with the internal surface of the capillary is treated within the framework of dielectric response theory. We analyze the distance of closest approach and the angular distributions of the highly charged ions at the exit of the microcapillary. We find the charge-state fraction of transmitted N6+ projectiles, in: good agreement with first measurements. Moreover, our calculations indicate that grazing collisions with the microcapillary surface hold the promise of direct observation of charge transfer and hollow-atom formation at a large distance from the surface. [less ▲]

Detailed reference viewed: 62 (8 UL)
Full Text
Peer Reviewed
See detailObservation of a threshold in potential sputtering of LiF surfaces
Hayderer, G.; Lemell, C.; Wirtz, Ludger UL et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2000), 164

A quartz-crystal microbalance technique is used for measuring total sputtering yields for LiF under impact of slow (20 eV, 100 eV, 500 eV and 1000 eV kinetic energy) singly and doubly charged ions. At low ... [more ▼]

A quartz-crystal microbalance technique is used for measuring total sputtering yields for LiF under impact of slow (20 eV, 100 eV, 500 eV and 1000 eV kinetic energy) singly and doubly charged ions. At low kinetic energies (less than or equal to 100 eV) potential sputtering (PS) (i.e., sputtering due to the projectiles potential energy) clearly dominates over kinetically induced sputtering. New insight into the mechanisms for PS is gained by determining the minimum potential energy necessary to induce PS. The measured potential energy threshold at around 10 eV provides evidence that PS can already be induced by the production of cold holes in the valence band of LiF via resonant neutralisation. (C) 2000 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 52 (0 UL)
Full Text
Peer Reviewed
See detailThreshold for potential sputtering of LiF
Hayderer, G.; Schmid, M.; Varga, P. et al

in Physical Review Letters (1999), 83(19), 3948-3951

We have measured total sputtering yields for impact of slow (less than or equal to 100 eV) singly and doubly charged ions on LiF. The minimum potential energy necessary to induce potential sputtering (PS ... [more ▼]

We have measured total sputtering yields for impact of slow (less than or equal to 100 eV) singly and doubly charged ions on LiF. The minimum potential energy necessary to induce potential sputtering (PS) from UF was determined to be about 10 eV. This threshold coincides with the energy necessary to produce a cold hole in the valence band of LiF by resonant neutralization. This allows the first unambiguous identification of PS induced by cold holes. Further stepwise increase of the sputtering yield with higher projectile potential energies provides evidence for additional defect-mediated sputtering mechanisms operative in alkali halides. [less ▲]

Detailed reference viewed: 37 (0 UL)