Imaging Pauli repulsion in scanning tunneling microscopy

Phys Rev Lett. 2010 Aug 20;105(8):086103. doi: 10.1103/PhysRevLett.105.086103. Epub 2010 Aug 20.


A scanning tunneling microscope (STM) has been equipped with a nanoscale force sensor and signal transducer composed of a single D2 molecule that is confined in the STM junction. The uncalibrated sensor is used to obtain ultrahigh geometric image resolution of a complex organic molecule adsorbed on a noble metal surface. By means of conductance-distance spectroscopy and corresponding density functional calculations the mechanism of the sensor and transducer is identified. It probes the short-range Pauli repulsion and converts this signal into variations of the junction conductance.