The Features of the Electron Exchange of Ions with Metal Nanoclusters

The results of a theoretical and computational study of the electron exchange of ions with metal nanoclusters are presented. Scanning tunneling microscopy and electron exchange in scattering of slow ions are used widely in experimental studies of the electronic structure and surface reactivity of metal nanoclusters. Due to the complexity of direct experiments, computer simulation is an important tool for nanostructure analysis. The results of calculation of the eigenvalues of the electron wave function accurately characterize the spatial distribution of the electron density on the nanocluster surface determined using scanning tunneling microscopy. The electron energy inside a small nanocluster is quantized, and the spatial distribution of the electron density is discrete. The quantization of electron energy (discrete electronic structure) has a significant influence on resonant electron processes, including the electron exchange of ions with nanoclusters and electron tunneling in scanning tunneling microscopy. The model problem of electron tunneling from a negative ion to a nanocluster was used as an example to demonstrate that the discrete electronic structure is manifested in the form of a quantum-size effect of electron exchange and a nonmonotonic dependence of the differential conductivity on the bias voltage. A quantitative explanation for the experimentally observed order-of-magnitude enhancement (compared to bulk samples) of the probability of neutralization of alkali metal ions on metal nanoclusters is also provided.