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Fast-scan spm/stm microscopy

imaging high-speedmicroscopy fastmicroscopy scanning tunnellingscan resonance frequencyscanning probe

Introduction

The proposed invention relates to a method for driving scanning probe microscopes (SPMs) at elevated scan frequencies, even above their resonance frequencies, while maintaining a spatial resolution comparable to the slow, standard, scanning modes. Our method selects the fast scanning frequency windows where measurements are possible by a simple protocol capable to characterize the resonances of the whole microscope assembly.

Technical features

Time resolution of commercial SPM instruments represents one of their limitations since the typical image acquisition times are of the order of seconds or more; consequently fundamental details of atomic scale dynamical processes occurring at surfaces are partially or totally lost. The scan speed is limited both by signal detection electronics and by mechanical resonances of the scanner. However, despite the fact that not all the mechanical resonances affect the STM image resolution, a method to unequivocally determine harmful resonances is still missing. Our method measures the response of the microscope read-out parameter (the tunnelling current for STM) while sweeping the frequency of excitation of the local probe movement: the spectrum regions where the response appears not to depend on the applied excitation frequency (plateau), designate operating frequencies adapted to achieve optimal imaging conditions.

Possible Applications

  • Fast-scan Microscopy;
  • Surface analysis (studies);
  • Catalysis;
  • Organics electronics;
  • Molecular electronics;
  • Electro-chemistry.

Advantages

  • Fast-scan on standard SPM/STM;
  • Low-cost upgrade;
  • High resolution;
  • High mechanical stability;
  • Reliability.