title: An approach to measure electromechanical properties of atomic and molecular junctions.
abstract: We describe a new setup for simultaneous measurements of force and current in conductive nanocontacts in a liquid environment with a high sampling rate and resolution. A lab-built current-to-voltage converter allows measurements of the current over seven orders of magnitude. As examples, we studied conductances and mechanical forces upon formation and breaking of gold atomic contacts and of two molecular junctions containing 1,2-di(4-pyridyl)ethyne (M1) and 1,4-di(4-pyridyl)buta-1,3-diyne (M2). We found that the forces required to deform or break gold atomic contacts depend critically on the surrounding medium. Further, they show non-linear behaviour in dependence of the number N of gold atoms detached. The electromechanical properties of the two types of molecular junctions upon stretching were analysed by correlating breaking forces with simultaneously measured junction conductances. A rather complex behaviour in a wide range of forces was discovered. Comparison of the current-probe atomic force microscopy experiments on the rupture of molecular junctions with STM-based break junction experiments enables the assignment of breaking forces of molecular junctions to the corresponding junction conductances.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland. ilya.pobelov@iac.unibe.ch
authors.forename: Ilya V
authors.initials: IV
authors.lastname: Pobelov
authors.forename: Gábor
authors.initials: G
authors.lastname: Mészáros
authors.forename: Koji
authors.initials: K
authors.lastname: Yoshida
authors.forename: Artem
authors.initials: A
authors.lastname: Mishchenko
authors.forename: Murat
authors.initials: M
authors.lastname: Gulcur
authors.forename: Martin R
authors.initials: MR
authors.lastname: Bryce
authors.forename: Thomas
authors.initials: T
authors.lastname: Wandlowski
mesh_terms: D000473:Alkanes / Q000737:chemistry; D001555:Benzene Derivatives / Q000737:chemistry; D004553:Electric Conductivity; D006046:Gold / Q000737:chemistry*; D055595:Mechanical Phenomena; D008958:Models, Molecular; D008968:Molecular Conformation; D012997:Solvents / Q000737:chemistry
chemical_list: C482494:1,3,5-trimethylenebenzene; D000473:Alkanes; D001555:Benzene Derivatives; D012997:Solvents; D006046:Gold; C012867:decane