title: Simulations of tip-enhanced optical microscopy reveal atomic resolution.
abstract: We have performed finite element electromagnetic analysis of 'apertureless' scanning near-field optical microscope tips. A variety of radii was considered, from 40 nm down to 1 nm, and the enhancement of optical scattering from the region beneath the probe apex was modelled in air and water. We observed sizeable spectral shifts when the radius decreases, together with a surprising increase in the amount of scattering from small tips. The lateral resolution is considered, which is shown to be always smaller than the tip radius, and for 1-nm-radius tips can allow atomic resolution imaging with sufficient optical enhancement. Gold, silver, copper and aluminium were modelled as tip materials.
authors.affiliation: Institute for Materials and Processes, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh, EH9 3JL, UK. andy.downes@ed.ac.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Downes
authors.forename: Donald
authors.initials: D
authors.lastname: Salter
authors.forename: Alistair
authors.initials: A
authors.lastname: Elfick