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Etching Characteristics of Titanium Nitride in Chlorine-Based Plasma
摘要： In this study, we carried out an investigation on the etching characteristics of TiN thin films and the selectivity of TiN to PR in inductively coupled Cl2/Ar plasma. The maximum etch rate of the TiN thin films was 27 nm/min for a gas-mixing ratio of 4:16 sccm (Cl2/Ar). X-ray photoelectron spectroscopy analysis showed efficient destruction of the oxide bonds by ion bombardment as well as the accumulation of less-volatile reaction products on the etched surface. Field emission auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.
关键词： TiN,XPS,AFM
更新于2025-09-23 15:22:29
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Solvent effect on the morphology of the bee: structure observed by atomic force microscopy on bitumen sample
摘要： The objective of this work was to characterize the asphaltic cement penetration grade 30/45 (CAP 30/45) based on the morphology of nanostructures called 'bee' structure observed and its modification when the binder was diluted in heptanes or toluene. The morphology of CAP30/45, toluene and heptane films was studied by Atomic Force Microscopy (AFM) tapping mode and showed typical 'bee' structure in asphaltic cement films, but this structure is not visible on the other films. While, toluene completely dissolved the bees, films attacked with heptane still presented some structures left.
关键词： nanostructures,AFM,asphaltene,bitumen
更新于2025-09-23 15:22:29
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High-fidelity probing of the structure and heterogeneity of extracellular vesicles by resonance-enhanced atomic force microscopy infrared spectroscopy
摘要： Extracellular vesicles (EVs) are highly specialized nanoscale assemblies that deliver complex biological cargos to mediate intercellular communication. EVs are heterogeneous, and characterization of this heterogeneity is paramount to understanding EV biogenesis and activity, as well as to associating them with biological responses and pathologies. Traditional approaches to studying EV composition generally lack the resolution and/or sensitivity to characterize individual EVs, and therefore the assessment of EV heterogeneity has remained challenging. We have recently developed an atomic force microscope IR spectroscopy (AFM-IR) approach to probe the structural composition of single EVs with nanoscale resolution. Here, we provide a step-by-step procedure for our approach and show its power to reveal heterogeneity across individual EVs, within the same population of EVs and between different EV populations. Our approach is label free and able to detect lipids, proteins and nucleic acids within individual EVs. After isolation of EVs from cell culture medium, the protocol involves incubation of the EV sample on a suitable substrate, setup of the AFM-IR instrument and collection of nano-IR spectra and nano-IR images. Data acquisition and analyses can be completed within 24 h, and require only a basic knowledge of spectroscopy and chemistry. We anticipate that new understanding of EV composition and structure through AFM-IR will contribute to our biological understanding of EV biology and could find application in disease diagnosis and the development of EV therapies.
关键词： spectroscopy,heterogeneity,nanoscale characterization,AFM-IR,extracellular vesicles
更新于2025-09-23 15:22:29
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DNA origami deposition on native and passivated molybdenum disulfide substrates
摘要： Maintaining the structural fidelity of DNA origami structures on substrates is a prerequisite for the successful fabrication of hybrid DNA origami/semiconductor-based biomedical sensor devices. Molybdenum disulfide (MoS2) is an ideal substrate for such future sensors due to its exceptional electrical, mechanical and structural properties. In this work, we performed the first investigations into the interaction of DNA origami with the MoS2 surface. In contrast to the structure-preserving interaction of DNA origami with mica, another atomically flat surface, it was observed that DNA origami structures rapidly lose their structural integrity upon interaction with MoS2. In a further series of studies, pyrene and 1-pyrenemethylamine, were evaluated as surface modifications which might mitigate this effect. While both species were found to form adsorption layers on MoS2 via physisorption, 1-pyrenemethylamine serves as a better protective agent and preserves the structures for significantly longer times. These findings will be beneficial for the fabrication of future DNA origami/MoS2 hybrid electronic structures.
关键词： atomic force microscopy (AFM),molybdenum disulfide (MoS2),1-pyrenemethylamine,pyrene,DNA origami,surface modification
更新于2025-09-23 15:22:29
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Modelling of ‘sub-atomic’ contrast resulting from back-bonding on Si(111)-7×7
摘要： It has recently been shown that ‘sub-atomic’ contrast can be observed during NC-AFM imaging of the Si(111)-7×7 substrate with a passivated tip, resulting in triangular shaped atoms [Sweetman et al. Nano Lett. 2014, 14, 2265]. The symmetry of the features, and the well-established nature of the dangling bond structure of the silicon adatom means that in this instance the contrast cannot arise from the orbital structure of the atoms, and it was suggested by simple symmetry arguments that the contrast could only arise from the backbonding symmetry of the surface adatoms. However, no modelling of the system has been performed in order to understand the precise origin of the contrast. In this paper we provide a detailed explanation for ‘sub-atomic’ contrast observed on Si(111)-7×7 using a simple model based on Lennard-Jones potentials, coupled with a flexible tip, as proposed by Hapala et al. [Phys. Rev. B 2014, 90, 085421] in the context of interpreting sub-molecular contrast. Our results show a striking similarity to experimental results, and demonstrate how ‘sub-atomic’ contrast can arise from a flexible tip exploring an asymmetric potential created due to the positioning of the surrounding surface atoms.
关键词： NC-AFM,sub-atomic,qPlus,sub-molecular
更新于2025-09-23 15:22:29
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Triptycene Based Fluorescent Polymers with Pendant Alkyl Chains: Interaction with Fullerene and Morphology of Thin Films
摘要： We report unique triptycene based alternating copolymers bearing long alkyl chains as pendants. Syntheses utilized 2,6-diethynyltriptycene and appropriate alkyloxyarene monomers polymerized via Sonogashira cross coupling reaction to yield triptycene based poly(phenylene ethynylene)s (TPPEs). Resulting polymers are soluble in organic solvents and were characterized by FT-IR, NMR, GPC, TGA, AFM, SEM, UV-visible and fluorescence spectroscopic techniques. Experimental results suggest polymers are thermally stable and fluorescent. The fluorescence emission was quenched in presence of fullerenes (C60 and C70) suggesting their strong host-guest interactions. The magnitude of binding constant between polymer and these fullerenes was determined to be in the order of 105 M-1.The effect of chain length on the morphology and wettability of polymers on silicon substrates were studied using atomic force microscope. Three distinct dewetting patterns viz., spherical domains, fractal and ring structures, were observed with variation in the pendant chain length. This ability to control the thin film morphology of polymers may have potential technological applications, which includes but is not limited to sensors, fluorescent coatings and organic electronics.
关键词： Triptycene,binding interaction with fullerene,AFM,fluorescence
更新于2025-09-23 15:21:21
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Frictional Characteristics of Suspended MoS <sub/>2</sub>
摘要： Molybdenum disulfide (MoS2), a booming layered two-dimensional (2D) nanomaterial, has gain intensive interests for its remarkable physical properties. In this work, the friction characteristics of suspended MoS2 are systematically investigated with atomic force microscopy (AFM). The friction on the suspended MoS2 is much larger than that on the supported MoS2 because of the softening bending rigidity and easier formation of puckering at the AFM tip-MoS2 contact interface, and the difference would increases with the applied load. Similar to the supported MoS2, the friction on the suspended MoS2 also decreases with the increasing layers because of the enhanced bending rigidity. The friction on the suspended MoS2 is relatively insensitive to the shapes of holes below but sensitive to the dimensions. This work can provide beneficial guidance for the diverse design requirements of MoS2-based nanoelectromechanical devices.
关键词： friction,suspended,Molybdenum disulfide,puckering effect,bending rigidity,AFM,atomic force microscopy,MoS2,supported
更新于2025-09-23 15:21:21
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Ultrathin Molecular Layer Junctions Based on Cyclometalated Ruthenium Complexes
摘要： A cyclometalated ruthenium complex has been designed to be immobilized on a surface by diazonium electroreduction. Modified surfaces have been obtained and fully characterized by XPS, electrochemistry and AFM. Molecular junctions consisting of Ru(bpy)2(ppy) oligomer using direct top-coat evaporation are presented.
关键词： XPS,diazonium electroreduction,molecular junctions,AFM,cyclometalated ruthenium complexes,electrochemistry
更新于2025-09-23 15:21:21
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Abrasive flow machining (AFM) finishing of conformal cooling channels created by selective laser melting (SLM)
摘要： Conformal cooling channels are widely adopted in the mold industry because of rapid and uniform cooling during injection molding. These complicated cooling channel geometries become feasible via selective laser melting (SLM) technology. However, the SLM fabricated internal channel surface shows high surface roughness of about 10 μm Ra. This rough surface can cause stress concentration, reducing the fatigue life of the mold. Therefore, the objective of this study is to investigate the surface finish of the SLM fabricated conformal channels by abrasive flow machining (AFM), which is widely used in the surface finishing of internal channels. To fulfill this objective, a combination of single/multiple and straight/helical channels for conformal cooling channel geometries are employed. Seven different types of conformal cooling channels (?3mm) inside the bar are fabricated using SLM. The bar is put in the AFM fixture, and the internal channels are polished by flowing AFM media (ULV50%-54) through the channel at the same extrusion pressure of 80 bars for ten cycles. Fourteen bars (seven before AFM and seven after AFM) are machined to have the internal channel surfaces exposed for surface roughness measurement. Surface topographies of the exposed surfaces of seven types of internal channels are obtained using focus variation microscopy. The areal roughness parameters, such as arithmetical mean height (Sa) on the internal channel surfaces before and after AFM. By comparing SLM as-built conformal channel surfaces with AFM finished ones, AFM is shown to be effective in improving all SLM conformal cooling channels’ arithmetical mean height, Sa. Areal roughness parameters, such as developed interfacial area ratio (Sdr), root mean square gradient (Sdq), reduced peak height (Spk), reduced valley height (Svk), and skewness (Ssk), on those internal surfaces, were found to be sensitive to surface finishing by AFM.
关键词： Conformal cooling channel,Selective laser melting (SLM),Abrasive flow machining (AFM),Straight/helical and single/multiple channels,Areal roughness parameters
更新于2025-09-23 15:21:01
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Predicted bandgap opening in highly-oriented wrinkles formed in chemical vapour deposition grown graphene
摘要： We present a combined atomic force microscopy and Raman spectroscopy study of wrinkle formation in chemical vapour deposition graphene. Graphene was grown on copper and repeatedly transferred onto a SiO2 substrate to form a four-layer graphene stack. By means of depositing two electrodes with a small gap of 1μm on top of graphene, we can generate a long wrinkle along the channel. Such a wrinkle is pronounced and seems to form at the expense of other wrinkles otherwise present. Along the wrinkle, the strain measured by both atomic force microscopy and polarized Raman is revealed to be of a biaxial type, which is shown, through atomistic modelling, is predicted to produce a sizeable bandgap opening of up to 0.4 eV. Since graphene is normally a zero bandgap material, its applications as an electronic material for devices can be limited. The approach presented in this work could lead to graphene exhibiting a controllable bandgap similar to a semiconductor material that could, therefore, be exploited for the fabrication of graphene-based electronic devices.
关键词： DFT,AFM,Raman spectroscopy
更新于2025-09-23 15:21:01