Submolecular imaging with single particle atomic force sensors

Scanning probe methods with decorated tips is a new trend in surface study. An application of complex probe like a tip with an attached single molecule or single atom allows to get new details about the surface properties. It has been shown that the scanning tunnelling hydrogen microscopy (STHM) approach can reach atomic scale resolution and reveals intermolecular interactions. Because of the complexity, this new rapidly developing area is not yet fully understood. In this work systematic studies of tips decorated with Xe, H2, D2, CO, CH4 was carried out. The tip with a single atom or a single molecule creates a single particle sensor that simultaneously performs the function of an atomicscale force sensor and a signal transducer, which couples the short-range force acting on the tip to the tunnelling conductance of the junction. In some cases the sensor-transducer function of the decorated STM tips can be quantitatively calibrated. Differences in the performance of the studied sensors suggest that the sensor functionality can be modified by tuning the interaction between the sensor particle and the STM tip. Based on forcefield calculations, theoretical analysis of the single particle sensor shows an interrelation between the relative movement of the particle on the tip and contrast structure of the surface images