Interaction of low energy reactive ions with surfaces. III. Scattering of 30–200 eV Ne+, O+, C+, and CO+ from Ni(111)

Abstract

Time-of-flight (TOF) and energy distributions of 30–200 eV Ne+, O+, C+, and CO+ scattered from Ni(111) have been investigated using pulsed ion beam techniques and classical trajectory simulations. The experiments probe the interaction potentials and the applicability of the binary collision approximation in the low energy range. The experimental scattering energies are in good agreement with the energies predicted by the classical treatment. Scattering of atomic projectiles at primary energies as low as 30 eV (scattered energies ∼15 eV) has been detected and is characterized by sharp scattering peaks. The lower limit of detectability is determined by the sensitivity of the detector to slow neutrals. The reactive ions are completely neutralized in the scattering collision while some of the Ne+ ions survive single scattering events. Scattering of molecular CO+ produces a broad scattered flux distribution due to partial dissociation and scattering of both molecular and atomic species. Trajectory simulations have been performed using a purely repulsive Biersack–Ziegler potential and a Biersack–Ziegler potential combined with a Morse potential to include an attractive component. The importance of the attractive potential in describing the trajectories of the reactive ions increases with decreasing ion energy. This attractive potential is shown to be responsible for preferential neutralization of reactive ions by altering the trajectories so that the distance of closest approach is shorter and the time spent near the surface is longer, thus enhancing electronic interaction between colliding species. Energy level diagrams are used to discuss the neutralization transitions and the differences between the reactive and noble ions.

Positive- and negative-ion formation in low-energyO+-Cu(001) scattering

“…Observations of O Ϫ have previously been explained by several authors using resonant charge-transfer mechanisms. 3,5,18,20,45,46 Quantitative predictions of resonant charge-transfer probabilities require treating the intrinsic multistate character of this problem, including that arising from the degenerate p electrons in oxygen; 18 this is beyond the scope of this paper.…”

Balmer line emission from low-energy impact of H+, H2+ and H3Ławicki1, Pranszke2, Kowalski3 et al. 2007Nuclear Instruments and Methods in Physics Research Section B: 8010View full textAdd to dashboardCite

“…With these they form intermediate molecular orbitals, which describe an electronically excited state of the system. As the two components separate again, diabatic crossings between the potential energies of the transient molecule lead the system into states which correlate at infinity with excited products [39][40][41][42]. Unlike AN, this reaction step does involve the motion of heavy particles and is therefore much slower than the AN step, and subsequent to it.…”

Measurements of ion‐induced ferroelectric emission and surface charge dynamics on LiTaO3(0001) by time‐of‐flight scattering and recoiling spectrometry (TOF‐SARS)

“…No sputtering was performed in order to preserve the nominal atomic composition of the sample surface. 25 Ion scattering experiments were carried out in a homebuilt TOF-SARS system similar to the one described by Rabalais et al 21 A schematic diagram of the system is shown in Fig. 1.…”