Coordination-resolved Local Bond Strain And 3p Energy Entrapment Of K Atomic Clusters And K(110) Skins

The novel properties of low-dimensional materials and solid skin have made them attracted much attention, because of these properties can hardly be seen from their single atom and bulk. With the size of a substance down near to nanometer scale, it poses some novel physical properties, such as lower melting point, semi-conductor-like properties, etc. Relaxation of bond among under-coordinated atoms at a solid skin and in an atomic cluster, their associated energies and the localization and polarization of electrons are of importance to the behaviour of material at these atomic sites. Nanomaterials and solid skin are different from the corresponding bulk and single atom owing to the high fraction of under-coordinated atoms and their interaction.We have examined the atomic coordination effect on the surface relaxation, binding energy, energetic behaviour of clectrons localized, local bond strain, and the 3p core-level shift of K(110) skin and nanoclusters using a combination of the bond order-length-strength correlation notion, tight-binding approach, density functional theory calculations, photoelectron spectroscopy measurements and zone-selective photoelectron spectroscopy. The detailed work and results achieved are as follows:(i) It turns out that the 3p core-level shifts from 15.595 ± 0.003 eV for an isolated K atom by 2.758 eV up to the bulk value of 18.353 eV using the method of combining the BOLS-TB correlation algorithm with the high-resolution XPS measurements and ZPS spectroscopy;(ii) the effective atomic coordination number reduces from the bulk value of 12 to 3.93 for the first layer and to 5.81 for the second layer of K(110) skin associated with the local lattice strain of 12.76%, a binding energy density 72.67%, and atomic cohesive energy-62.46% for the skin; and,(iii) we obtain several kinds of different structure and density of states for K clusters using DFT calculation, K cluster size reduction lowers the effective atomic coordination number and enhances further the skin electronic attribution. Results have revealed that the 3p core-level shifts of K(110) and nanoclusters originate from perturbation of the Hamiltonian by atomic under-coordination induced charge densification and quantum entrapment.Incorporating the DFT calculations and XPS measurements has led to consistent insight into the physical origin of the localized edge states of K solid skin and clusters which confirmed the BOLS-TB predictions of the atomic CN effects on the local bond relaxation, electron binding-energy shift, atomic cohesive energy, and their coordination- resolved shifts of K skins and nanoclusters. These quantitative informations are helpful for applying K skins and nanoclusters in practical application, such as catalytic enhancement, applications in electronics and optics, and designing nanocrystals with desired structures and properties.