Energy Dissipation in Dynamic Force Spectroscopy of PTCDA on Ag-Si(111) .RAD.3*.RAD.3

Abstract

The energy dissipation of different phases of PTCDA (3,4,9,10-perylene-tetracarboxylic-dianhydride) on AgSi(111) √ 3 × √ 3 was investigated by means of atomic force spectroscopy using a custom-built low-temperature atomic force microscope (LT-AFM). The energy dissipation is due to non-conservative forces between the tip and sample. We present preliminary energy dissipation data measured when the tip was placed above four different PTCDA superstructures. While one of them showed energy dissipation, the others did not. The dissipation process seems to be critically influenced by the junction geometry; a chemical bound between the tip apex and a specific site of the molecular layer might be one channel for the dissipation.

Communication: Substrate induced dehydrogenation: Transformation of octa-ethyl-porphyrin into tetra-benzo-porphyrin

“…The molecules are evaporated from a tiny oven with a quartz crucible directly a) Electronic mail: rolf.moeller@uni-due.de heated by a tungsten filament. 21 Prior to the measurements the oven was carefully outgassed. The flow of molecules was checked by a quadrupole mass spectrometer covering the range from 1 to 1028 amu.…”

Surface‐Induced Dechlorination of FeOEPCl on Cu(111)

“…The experiments were performed by using a self‐built low‐temperature STM/atomic force microscope (LT‐STM/AFM),25 which was operated in an ultra‐high vacuum at T =80 K. The Cu(111) substrate was prepared through several cycles of Ar + ‐sputtering and annealing at around 900 K. The molecules were sublimated from a self‐built transferable furnace 26. Prior to the deposition of the molecules onto the surface, the flux of molecules from the source was studied by using a quadrupole mass spectrometer (Pfeiffer QMS 422) with a mass range of up to 1024 u.…”

Kinetic effects of TiO2 fine particles and nanoparticles aggregates on the nanomechanical properties of human neutrophils assessed by force spectroscopy

“…Dissipated energy results from tip and sample interactions as a function of either the gap distance or applied bias [65]. Vorden et al [66] described non-conservative forces as being strongly dependent on these interactions. Energy dissipation can be related to sample viscoelastic properties [67].…”