Laura Adams

Observation of discrete energy levels in a quantum confined system.

Low temperature scanning tunneling microscope images and spectroscopic data have been obtained on subnanometer size Pb clusters fabricated using the technique of buffer layer assisted growth. Discrete energy levels were resolved in current-voltage characteristics as current peaks rather than current steps. Distributions of peak voltage spacings and peak current heights were consistent with Wigner-Dyson and Porter-Thomas distributions, respectively, suggesting the relevance of random matrix theory to the description of the electronic eigenstates of the clusters. The observation of peaks rather than steps in the current-voltage characteristics is attributed to a resonant tunneling process involving the discrete energy levels of the cluster, the tip, and the states at the interface between the cluster and the substrate surface.

Spectroscopic Evidence Of Discrete Energy Levels In Nanosize Clusters Of Metal Atoms Using A Low Temperature STM

A new method of obtaining spectroscopic information about clusters is realized though the interplay between the surface states at a metal‐semiconductor interface and the discrete electronic energy levels of nanosize Pb clusters. When these surface states come into registry with the energy levels of the cluster, resonant peaks emerge in the I(V) characteristics. The histograms of the peak intensities and spacing are consistent with the Porter‐Thomas and Wigner‐Dyson distributions, respectively.