Dual resonance excitation system for the contact mode of atomic force microscopy

Abstract

We propose an improved system that enables simultaneous excitation and measurements of at least two resonance frequency spectra of a vibrating atomic force microscopy (AFM) cantilever. With the dual resonance excitation system it is not only possible to excite the cantilever vibrations in different frequency ranges but also to control the excitation amplitude for the individual modes. This system can be used to excite the resonance frequencies of a cantilever that is either free of the tip-sample interactions or engaged in contact with the sample surface. The atomic force acoustic microscopy and principally similar methods utilize resonance frequencies of the AFM cantilever vibrating while in contact with the sample surface to determine its local elastic modulus. As such calculation demands values of at least two resonance frequencies, two or three subsequent measurements of the contact resonance spectra are necessary. Our approach shortens the measurement time by a factor of two and limits the influence of the AFM tip wear on the values of the tip-sample contact stiffness. In addition, it allows for in situ observation of processes transpiring within the AFM tip or the sample during non-elastic interaction, such as tip fracture.

Mechanical characterization of porous nano-thin films by use of atomic force acoustic microscopy

“…The amplitude of the vibrations depends strongly on the excitation frequency and is measured by a laser beam deflected from the cantilever to a photodiode detector. In our system, the deflection component of the photodiode signal is analyzed by use of fast Fourier transform (FFT) methods [27,49]. The results presented in this study were obtained using AFAM in the single-point spectroscopy mode.…”

“…The measurements can be performed as a function of the increasing (load) as well as decreasing load (unload). The details concerning the simultaneous excitation of the two or more contact resonance spectra can be found in [49]. Once the contact resonance frequencies are measured, the values of the tip-sample contact stiffness k * can be calculated.…”

Vibrational shape tracking of atomic force microscopy cantilevers for improved sensitivity and accuracy of nanomechanical measurements

“…Measurements of f and Q can be related to spring and dashpot boundary conditions in a dynamic Euler-Bernoulli beam model, and a contact mechanics model can then be utilized to determine the elastic and viscoelastic properties of the sample. CR-AFM has been used to measure the nanomechanical properties of a wide variety of material systems (see, e.g., [7][8][9][10]) and can be adapted to nanomechanical mapping [11][12][13][14].…”

General Resolution Enhancement Method in Atomic Force Microscopy Using Deep Learning

“…In this study, a very deep convolution neural network is developed to derive a high-resolution topography image from a low-resolution topography image. Hence, several methods and techniques were proposed to enhance the resolution and quality of the AFM images, such as by improving the shape and properties of the tip or cantilever, [11][12][13][14] the development and application of the multiple frequency excitation techniques, [15][16][17][18] the contour metrology, [19] The derived high-resolution AFM images are comparable with the experimental measured high-resolution images measured at the same locations.…”

“…[3][4][5] However, the unavoidable experimental errors, such as "tip crash," [6] the cross-talk between topographic and electrostatic information, [7] the large height variation of the sample surface, [8] and the influence by the properties of the sample or the ambient environment [9] can severely reduce the spatial resolution of the AFM images. Hence, several methods and techniques were proposed to enhance the resolution and quality of the AFM images, such as by improving the shape and properties of the tip or cantilever, [11][12][13][14] the development and application of the multiple frequency excitation techniques, [15][16][17][18] the contour metrology, [19] [10] Generally speaking, low-resolution images certainly contain insufficient information, which may cause some of the important features, including grain boundary, surface defect, dislocation and interface unclear or even ignored.…”