title: Contrast reversal and shape changes of atomic adsorbates measured with scanning tunneling microscopy.
abstract: Systematic, quantitative comparisons between scanning tunneling microscopy (STM) experiments and first principles simulations of O(2 x 2)/Ru(0001) have been performed. The shape of the atomic adsorbates in the images depends strongly on the tunneling resistance and changes reversibly from circular (high resistance) to triangular (low resistance). In addition, after adsorption of oxygen on the STM tip we observe a contrast reversal on the surface, confirmed by extensive numerical simulations.
authors.affiliation: Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Calleja
authors.forename: A
authors.initials: A
authors.lastname: Arnau
authors.forename: J J
authors.initials: JJ
authors.lastname: Hinarejos
authors.forename: A L
authors.initials: AL
authors.lastname: Vázquez de Parga
authors.forename: W A
authors.initials: WA
authors.lastname: Hofer
authors.forename: P M
authors.initials: PM
authors.lastname: Echenique
authors.forename: R
authors.initials: R
authors.lastname: Miranda