Figure 4: Anchor-dependent contact mechanics.
From: Roles of vacuum tunnelling and contact mechanics in single-molecule thermopower
(a) Equivalent circuit of molecular junctions consisting of m molecules with resistance RSMJ and thermovoltage V2 bridging a Au electrode gap. Contribution of direct tunnelling is included as the resistance Rgap and the tunnelling thermopower component Vgap connected in parallel. Rs is the thermovoltage sensing resistor connected in series to the junctions. (b) Direct tunnelling contribution. The thermovoltage versus conductance characteristics complies with the circuit model assuming quadruple-molecule junctions with variable size of vacuum gap with 1/Rgap from 1 × 10−4 G0 to 1 × 10−1 G0. (c) Energy-optimized structure of BDA quadruple-molecule junctions. (d) Seebeck coefficients S estimated by taking the thermopower of Au nanocontacts as reference. (e,f) Contact mechanics of BDA (e) and ABT (f). Junction images show energy-optimized structures. Arrows point toward stretching of junctions defined as the distance Lc between the molecule-linked Au atoms. Au-molecule bond lengths and angles at the both sides are plotted with respect to Lc.
