Systematic Achievement of Improved Atomic-Scale Contrast via Bimodal Dynamic Force Microscopy

Abstract

Judiciously matched experiments, calculations, and theory demonstrate that a higher sensitivity to short-range interactions and, consequently, improved resolution on the atomic scale can be achieved by bimodal noncontact dynamic force microscopy. The combination of sub-Angström tip oscillation at the second flexural resonance of a commercially available silicon cantilever with the commonly used large amplitude oscillation at the fundamental resonance frequency enables this performance improvement while avoiding potentially damaging jump-to-contact instabilities.

Fast nanomechanical spectroscopy of soft matter

“…In bimodal frequency modulation AFM, the frequency shift of any mode is related to the force by 23,41,42 …”

“…In the recent years, several methods have been proposed to complement the high spatial resolution of the force microscope with quantitative information about the mechanical properties of the interface [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] . In fact, the goal of combining topography with compositional contrast can be traced back to the origin of dynamic AFM with the development of phase-imaging AFM.…”

Atom manipulation on an insulating surface at room temperature

“…We use the recently developed bimodal dynamic mode AFM (bimodal d-AFM) [31][32][33] , in which the vertical and lateral tip-sample interactions are simultaneously detected via frequency shifts of the flexural Df ver and torsional resonance modes Df TR , respectively 34 . In this technique, the Df TR signal has extreme sensitivity to the atomic-scale interaction, and hence atomic resolution is reliably achieved in a wide range of the Z tip-sample distance.…”

Energy Loss Triggered by Atomic-Scale Lateral Force

“…The flexural and torsional modes can also be combined in the so-called bimodal operation [31][32][33] allowing simultaneous measurement of both normal and lateral interactions, with all the advantages of dynamic atomic force microscopy (AFM): In particular, it is possible to measure accurately lateral interactions at relatively close distance through the torsional signals, while the vertical tip-sample distance is controlled by the flexural frequency shift, giving…”