An ultrasmall amplitude operation of dynamic force microscopy with second flexural mode

Abstract

Selective detection of short-range interaction forces was carried out with the second flexural mode of a commercially available dynamic mode cantilever. A higher mode has a higher spring constant and a lower mechanical quality factor, which are suitable for the small amplitude operation in dynamic force microscopy. With 0.70Å amplitude of the second flexural mode, atomically resolved constant frequency shift images of the Si(111)−7×7 reconstructed surface were obtained. The ultrasmall amplitude operation enabled imaging with high stability, due to the detection of the interaction force gradients at relatively long distances from the sample surface, and is an effective way to observe reactive surfaces while avoiding modifications and damaging of the tip and the sample.

Measurement of the Casimir force between a spherical gold tip and Si(111)-(7 × 7) surfaces

“…A higher mode has a higher spring constant and a lower mechanical quality factor, which are suitable for the small amplitude operation in dynamic force microscopy. 34) In this study, the amplitude shifts induced by the swept bias voltage were measured at the second resonant frequency (526 kHz). Figure 3 shows the amplitude shifts induced by the swept bias voltage on the Si (111) surface with the spherical Au tip at five different tip-sample distances.…”

Wideband low-noise optical beam deflection sensor with photothermal excitation for liquid-environment atomic force microscopy

“…The higher flexural modes are also used for oscillating a cantilever with very small amplitude. 19 The higher harmonics of the fundamental resonance have been investigated in order to understand the nonlinear cantilever dynamics 20 and enhance the spatial resolution. 21,22 These examples of recent research illustrate the growing demand for wideband cantilever deflection sensors.…”

Measuring Electric Field Induced Subpicometer Displacement of Step Edge Ions

“…The potential variation of a stepped clean LiF (001) surface was measured with a commercially available Si cantilever (Nanosensor NCL-PPP) in bimodal operation mode [41], using the second flexural mode [42] and the torsional resonance [43]. The high effective stiffness k 2nd ¼ 1806 N=m of the second mode realizes stable small amplitude operation of the vertical tip-sample interaction, which can reduce the averaging effect of the lateral force detection.…”