title: Mechanics and chemistry: single molecule bond rupture forces correlate with molecular backbone structure.
abstract: We simultaneously measure conductance and force across nanoscale junctions. A new, two-dimensional histogram technique is introduced to statistically extract bond rupture forces from a large data set of individual junction elongation traces. For the case of Au point contacts, we find a rupture force of 1.4 ± 0.2 nN, which is in good agreement with previous measurements. We then study systematic trends for single gold metal-molecule-metal junctions for a series of molecules terminated with amine and pyridine linkers. For all molecules studied, single molecule junctions rupture at the Au-N bond. Selective binding of the linker group allows us to correlate the N-Au bond-rupture force to the molecular backbone. We find that the rupture force ranges from 0.8 nN for 4,4' bipyridine to 0.5 nN in 1,4 diaminobenzene. These experimental results are in excellent quantitative agreement with density functional theory based adiabatic molecular junction elongation and rupture calculations.
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Frei
authors.forename: Sriharsha V
authors.initials: SV
authors.lastname: Aradhya
authors.forename: Max
authors.initials: M
authors.lastname: Koentopp
authors.forename: Mark S
authors.initials: MS
authors.lastname: Hybertsen
authors.forename: L
authors.initials: L
authors.lastname: Venkataraman
mesh_terms: D055119:Elastic Modulus; D004553:Electric Conductivity; D006046:Gold / Q000737:chemistry*; D006244:Hardness; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013314:Stress, Mechanical
chemical_list: D006046:Gold