M.E. Dokukin, I. Sokolov
Keywords: AFM, new modes of operation, quantitative material properties, material properties at the nanoscale, compositional contrast
Summary:Here we describe development of a novel non-resonant oscillatory AFM mode, which we suggest to call “Ringing” mode. This mode is based upon utilizing a part of the AFM signal that is currently not used. This part of the signal has been considered parasitic (or noise) and, consequently, filtered out. The Ringing mode is a combination of the oscillatory non-resonant mode and a resonant one. It operates with the non-resonant feedback, but utilizes the signal information from the ringing of the AFM cantilever, free resonance oscillations of the cantilever which occur after detaching the AFM probe from a sample surface. Analyzing the amplitude of the ringing provides less noisy information. The absence of signal filtering produces fewer artifacts. Compared to its rival, non-resonant oscillatory AFM mode (for example, PeakForce QNM), it provides faster imaging (~10x for material property channels); it produces fewer artifacts; it generates less noise in some channels due to the signal averaging (for example, multiple adhesion amplitudes). In addition, it delivers novel imaging information: Restored adhesion; Dynamic creep phase shift; Viscoelastic adhesive loss; Adhesion height; Zero force height (the latter has been recently introduced by several companies). It works with the standard AFM probes used in non-resonant modes. We demonstrate the application of this mode to various polymers and bio-materials.