Tapping mode atomic force microscopy (AFM) provides phase images in addition to height and amplitude images. Although the behavior of tapping mode AFM has been investigated using mathematical modeling, comprehensive understanding of the behavior of tapping mode AFM still poses a significant challenge to the AFM community, involving issues such as the correct interpretation of the phase images. In this paper, the cantilever's dynamic behavior in tapping mode AFM is studied through a three dimensional finite element method. The cantilever's dynamic displacement responses are firstly obtained via simulation under different tip-sample separations, and for different tip-sample interaction forces, such as elastic force, adhesion force, viscosity force, and the van der Waals force, which correspond to the cantilever's action upon various different representative computer-generated test samples. Simulated results show that the dynamic cantilever displacement response can be divided into three zones: a free vibration zone, a transition zone, and a contact vibration zone. Phase trajectory, phase shift, transition time, pseudo stable amplitude, and frequency changes are then analyzed from the dynamic displacement responses that are obtained. Finally, experiments are carried out on a real AFM system to support the findings of the simulations.
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Polymers (Basel)
January 2025
School of Engineering, Institute for Materials and Processes, The University of Edinburgh, Sanderson Building, King's Buildings, Edinburgh EH9 3FB, UK.
The phase separation of high-density polyethylene (HDPE)-polypropylene (PP) blends was studied using atomic force microscopy in tapping mode to obtain height and phase images. The results are compared with those from scanning electron microscopy imaging and are connected to the thermomechanical properties of the blends, characterised through differential scanning calorimetry, dynamic mechanical analysis (DMA), and tensile testing. Pure PP, as well as 10:90 and 20:80 weight ratio HDPE-PP blends, showed a homogeneous morphology, but the 25:75 HDPE-PP blends exhibited a sub-micrometre droplet-matrix structure, and the 50:50 HDPE-PP blends displayed a more complex co-continuous nano/microphase-separated structure.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Faculty of Technical Chemistry, Institute of Chemical Technologies and Analytics, Technische Universität Wien, Vienna 1060, Austria.
Atomic force microscopy-infrared spectroscopy (AFM-IR) is a photothermal scanning probe technique that combines nanoscale spatial resolution with the chemical analysis capability of mid-infrared spectroscopy. Using this hybrid technique, chemical identification down to the single molecule level has been demonstrated. However, the mechanism at the heart of AFM-IR, the transduction of local photothermal heating to cantilever deflection, is still not fully understood.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
School of Civil Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
To achieve the assembled connection between dovetail profiled steel sheets and the boundary members in dovetail profiled steel concrete composite shear walls (DPSCWs), self-tapping screws were employed. Three DPSCW specimens connected with self-tapping screws were tested under combined axial and cyclic lateral loads to evaluate their hysteretic response, focusing on the influence of the number of self-tapping screws and the axial compression ratio. The self-tapping screw-connected DPSCWs exhibited a mixed failure mode, characterized by shear failure of the profiled steel sheets and compression-bending failure of multiple wall limbs divided by ribs on the web concrete.
View Article and Find Full Text PDFNanoscale
December 2024
Nanomaterials and Systems Laboratory, Major of Mechatronics Engineering, Faculty of Applied Energy Systems, Jeju National University, Jeju-si, Republic of Korea.
Metal-organic frameworks (MOFs) are porous crystalline materials with a metal ion coordinated to a ligand molecule. Recently, MOFs are being explored extensively for energy harvesting triboelectrification. However, the majority of MOFs are brittle and hard to grow, thus leading to poor device stability and flexibility.
View Article and Find Full Text PDFAnal Bioanal Chem
January 2025
Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan.
Mass spectrometry imaging (MSI) is a promising analytical method to visualize the distribution of lipids in biological tissues. To clarify the relationship between cellular distribution and lipid types in a tissue, it is crucial to achieve both an improvement in ion detection sensitivity and a reduction in the ionization area. We report methods for improving the efficiency of ion transfer to a mass spectrometer and miniaturizing the extraction area of a sample for tapping-mode scanning probe electrospray ionization (t-SPESI), atmospheric pressure sampling, and ionization methods.
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