Quantum size effects in adatom island decay

TL;DR

This study investigates quantum size effects in the decay of Ag adatom islands on Ag(111), revealing that electron confinement causes non-monotonic decay rates at specific island sizes.

Contribution

It demonstrates that quantum size effects influence island decay rates, highlighting the role of electron confinement in surface atom detachment barriers.

Findings

Decay rates vary non-monotonically with island size.

Quantum size effects cause decay rate decreases at specific diameters.

Electron confinement enhances detachment barriers at certain sizes.

Abstract

The decay of hexagonal Ag adatom islands on top of larger Ag adatom islands on a Ag(111) surface is followed by a fast scanning tunneling microscope. Islands do not always show the expected increase in decay rate with decreasing island size. Rather, distinct quantum size effects are observed where the decay rate decreases significantly for islands with diameters of 6 nm, 9.3 nm, 12.6 nm, and 15.6 nm. We show that electron confinement of the surface state electrons is responsible for this enhancement of the detachment barrier for adatoms from the island edge.