Effects of adsorbates on charge exchange in Li+ ion scattering from Ni(100)

Abstract

Resonant charge transfer during the backscattering of 3.0 keV Li ϩ from hydrogen-and iodine-covered Ni͑100͒ is probed with time-of-flight spectroscopy. Hydrogen adsorption on Ni͑100͒ induces only a small increase of the surface work function and the neutralization probabilities for backscattered Li are not significantly affected. Iodine adsorbs with some net negative charge, so that a dipole directed into the surface is expected. Such a dipole would increase the work function thereby decreasing the neutralization probability. Iodine adsorption decreases the work function of Ni͑100͒, however, and the neutralization probabilities for Li scattered from the iodine sites are always larger than for scattering from nickel sites. These results suggest that the local charge density associated with adsorbed iodine is not uniform.

NiAl(110) Surface as a Template for Growing Transition Metal Linear Atomic Chains: A DFT Investigation

“…Conversely, when the adsorbate is less electronegative, a negative workfunction change arises from a donation of charge from the adsorbate to the surface. However, this general trend is not always kept, and different exceptions have been reported in the literature. − In particular, the systems considered here do not obey that common rule, and the interpretation must be done taking into account both the electronegativities and the polarizabilities of the adatoms …”

Adsorption of Pd, Pt, Cu, Ag, and Au Monomers on NiAl(110) Surface: A Comparative Study from DFT Calculations

“…Other authors have found systems in which similar irregularities can be observed. Thus, the adsorption of I to Ni(100) or Pt (111) has been reported as inducing charge transfer from the surface to the adsorbate and decreasing the work function by around 1 eV. Migani et al reported that the work function change induced by the presence of an adsorbed halide can be either positive or negative, depending on the surface metal .…”

The Effects of Hydrogen Annealing on Carbon Nanotube Field-Effect Transistors

“…Ni has a high work function of 5.2 eV, similar to that for Pd, and Al has a lower work function of 4.3 eV. Previous studies reported [ 21 , 22 ] that the work function of Ni is unaffected by hydrogen annealing. Thermo-transport measurements of hydrogen in metals showed that the hydrogen concentration in Ni was smaller than one-hundredth of those in Pd and Ti.…”