Temperature-Dependence of Water Bridge Formation in Atomic Force Microscopy

2003 ◽  
Author(s):  
Brent A. Nelson ◽  
Mark A. Poggi ◽  
Lawrence A. Bottomley ◽  
William P. King
Keyword(s):  
Temperature Dependence ◽  
Capillary Condensation ◽  
Heated Surface ◽  
High Surface ◽  
Water Evaporation ◽  
Water Bridge ◽  
Force Microscopy ◽  
Atomic Force ◽  
Localized Heating ◽  
Low Humidity

When an Atomic Force Microscope (AFM) is operated in air, capillary condensation induces meniscus formation between the AFM tip and substrate. At present, no models account for the temperature-dependence of meniscus formation. This paper describes experiments measuring capillary forces between an AFM tip and mica at various temperatures and times. At low humidity, the capillary force decreases with increasing surface temperature in a manner unaccounted for by merely the dependence of water surface energy on temperature. We propose that this is due to water evaporation off the heated surface. The adhesion is also shown to decrease significantly with time until stabilizing after approximately an hour of experiments. Localized heating of the surface by the AFM laser is proposed as the cause of adhesion decrease. The decrease in force occurring at high surface temperatures implies a reduction in meniscus size that may potentially improve the resolution of AFM-based nanolithography techniques.

scholarly journals Influence of Nanocrystalline Palladium Morphology on Alkaline Oxygen Reduction Kinetics

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 566 ◽  
Author(s):  
Eliran Hamo ◽  
Avichay Raviv ◽  
Brian A. Rosen
Keyword(s):  
Oxygen Reduction ◽  
High Surface ◽  
Reduction Reaction ◽  
Membrane Electrode ◽  
X Ray Diffraction ◽  
Rotating Disc ◽  
Force Microscopy ◽  
Atomic Force ◽  
Orr Kinetics ◽  
Disc Electrodes

The structure sensitivity of the alkaline oxygen reduction reaction (ORR) on palladium is of great interest as cost considerations drive the need to find a replacement for platinum catalysts. The kinetics of alkaline ORR were investigated on nanocrystalline palladium (Pd) films with domain sizes between 14 and 30 nm that were synthesized by electrodeposition from aqueous electrolytes. Ten Pd films were prepared under varying electrodeposition parameters leading to each having a unique texture and morphology. The sensitivity of initial alkaline ORR kinetics to the Pd surface structure was evaluated by measuring the kinetic current density and number of electrons transferred for each film. We show through scanning electron microscopy (SEM), x-ray diffraction (XRD), atomic force microscopy (AFM), and voltammetry from rotating disc electrodes (RDEs) that the fastest alkaline ORR kinetics are found on Pd surfaces with high surface roughness, which themselves are composed of fine grains. Such a study is useful for developing membrane electrode assemblies (MEAs) based on directly electrodepositing catalyst onto a conductive diffusion layer.

scholarly journals Towards an Understanding of Crystallization by Attachment

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 463
Author(s):  
Haihua Pan ◽  
Ruikang Tang
Keyword(s):  
Capillary Condensation ◽  
Force Measurements ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Driving Mechanisms ◽  
Atomic Force ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Hydration Layers

Crystallization via particle attachment was used in a unified model for both classical and non-classical crystallization pathways, which have been widely observed in biomimetic mineralization and geological fields. However, much remains unknown about the detailed processes and driving mechanisms for the attachment. Here, we take calcite crystal as a model mineral to investigate the detailed attachment process using in situ Atomic Force Microscopy (AFM) force measurements and molecular dynamics simulations. The results show that hydration layers hinder the attachment; however, in supersaturated solutions, ionic bridges are formed between crystal gaps as a result of capillary condensation, which might enhance the aggregation of calcite crystals. These findings provide a more detailed understanding of the crystal attachment, which is of vital importance for a better understanding of mineral formation under biological and geological environments with a wide range of chemical and physical conditions.

Biopolymer Blends as Potential Biomaterials and Cosmetic Materials

2013 ◽  
Vol 583 ◽  
pp. 95-100 ◽  
Author(s):  
Alina Sionkowska ◽  
Katarzyna Lewandowska ◽  
A. Planecka ◽  
P. Szarszewska ◽  
K. Krasinska ◽  
...  
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Surface Free Energy ◽  
Silk Fibroin ◽  
High Surface ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Polymeric Blends ◽  
Contact Angle Measurements

Blends of two polymer, namely chitosan with silk fibroin or partially hydrolysed polyacrylamide (HPAM) were prepared. The surface properties of chitosan/silk fibroin and chitosan/HPAM blended films were investigated using the technique of Atomic Force Microscopy (AFM) and by means of contact angle measurements allowing the calculation of surface free energy. Measurements of the contact angle for diiodomethane (D), and glycerol (G) on the surface of chitosan films and chitosan/silk fibroin films were made and surface free energy was calculated. It was found that chitosan/silk fibroin blend surface is enriched in high surface energy component i.e. silk fibroin. The surface roughness of chitosan, silk fibroin, HPAM, chitosan/silk fibroin and chitosan/HPAM blended films differs with the composition of the blend. Film-forming polymeric blends can be potentially used as biomaterials and cosmetic materials.

scholarly journals Nanoscale Molecular Characterisation of Hair Cuticles using Integrated AFM-IR

2020 ◽  
Author(s):  
A. P. Fellows ◽  
M. T. L. Casford ◽  
P. B. Davies
Keyword(s):  
Chemical Structure ◽  
High Surface ◽  
Great Majority ◽  
Diffraction Limit ◽  
Chemical Investigation ◽  
Molecular Characterisation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Spectroscopy ◽  
Significant Chemical

AbstractThe nanometre-scale topography and chemical structure of hair cuticles has been investigated by vibrational spectroscopy and imaging in two spectral regions. The combination of Atomic Force Microscopy with a tuneable infrared laser (AFM-IR) circumvents the diffraction limit that has impaired traditional infrared spectroscopy, facilitating surface spectroscopy at ultra-spatial resolution. The variation in protein and lipid content of the cuticle cell surface approaching its edge, as well as the exposed layered structure of the cell at the edge itself, was investigated. Furthermore, the contribution of cystine-related products to the cuticle layers was determined. The variation of protein, lipid and cystine composition in the observed layers, as well as the measured dimensions of each, correspond closely to that of the epicuticle, A-layer, exocuticle and endocuticle layers of the cuticle cell sub-structure.Statement of SignificanceUsing AFM-IR to analyse the nanoscale cuticle features is both significant and novel in the field. Thus far, the great majority of work on the chemical investigation of the structure of hair has been limited to bulk measurements, or subject to the diffraction limit associated with traditional IR spectroscopies and microscopies. AFM-IR circumvents this diffraction limit and allows nanometre-scale, localised chemical investigation with high surface selectivity. While non-chemical investigations, e.g. those using Transmission Election Microscopy, have previously shown cuticles to have a layered substructure, AFM-IR sheds light on significant chemical variations of protein and lipid compositions within such layers, enabling their quantification.

scholarly journals A highly sensitive safrole sensor based on polyvinyl acetate (PVAc) nanofiber-coated QCM

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kuwat Triyana ◽  
Aditya Rianjanu ◽  
Doni Bowo Nugroho ◽  
Ahmad Hasan As’ari ◽  
Ahmad Kusumaatmaja ◽  
...  
Keyword(s):  
Response Time ◽  
Polyvinyl Acetate ◽  
Limit Of Detection ◽  
High Surface ◽  
High Surface Area ◽  
Average Diameter ◽  
Promising Alternative ◽  
Force Microscopy ◽  
Atomic Force ◽  
Highly Sensitive

Abstract A novel, highly sensitive and selective safrole sensor has been developed using quartz crystal microbalance (QCM) coated with polyvinyl acetate (PVAc) nanofibers. The nanofibers were collected on the QCM sensing surface using an electrospinning method with an average diameter ranging from 612 nm to 698 nm and relatively high Q–factors (rigid coating). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the PVAc nanofiber surface morphology, confirming its high surface area and roughness, which are beneficial in improving the sensor sensitivity compared to its thin-film counterpart. The as-spun PVAc nanofiber sensor could demonstrate a safrole limit of detection (LOD) of down to 0.7 ppm with a response time of 171 s and a sensitivity of 1.866 Hz/ppm. It also showed good reproducibility, rapid response time, and excellent recovery. Moreover, cross-interference of the QCM sensor response to non-target gases was investigated, yielding very low cross-sensitivity and high selectivity of the safrole sensor. Owing to its high robustness and low fabrication cost, this proposed sensing device is expected to be a promising alternative to classical instrumental analytical methods for monitoring safrole-based drug precursors.

scholarly journals Effect of Gelation Temperature on the Molecular Structure and Physicochemical Properties of the Curdlan Matrix: Spectroscopic and Microscopic Analyses

2020 ◽  
Vol 21 (17) ◽  
pp. 6154
Author(s):  
Barbara Gieroba ◽  
Anna Sroka-Bartnicka ◽  
Paulina Kazimierczak ◽  
Grzegorz Kalisz ◽  
Izabela S. Pieta ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Surface ◽  
Attenuated Total Reflection ◽  
Force Microscopy ◽  
Surface Sensitivity ◽  
Atomic Force ◽  
Wide Range ◽  
The Matrix ◽  
Ft Ir ◽  
Ir And Raman

In order to determine the effect of different gelation temperatures (80 °C and 90 °C) on the structural arrangements in 1,3-β-d-glucan (curdlan) matrices, spectroscopic and microscopic approaches were chosen. Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) and Raman spectroscopy are well-established techniques that enable the identification of functional groups in organic molecules based on their vibration modes. X-ray photoelectron spectroscopy (XPS) is a quantitative analytical method utilized in the surface study, which provided information about the elemental and chemical composition with high surface sensitivity. Contact angle goniometer was applied to evaluate surface wettability and surface free energy of the matrices. In turn, the surface topography characterization was obtained with the use of atomic force microscopy (AFM) and scanning electron microscopy (SEM). Described techniques may facilitate the optimization, modification, and design of manufacturing processes (such as the temperature of gelation in the case of the studied 1,3-β-d-glucan) of the organic polysaccharide matrices so as to obtain biomaterials with desired characteristics and wide range of biomedical applications, e.g., entrapment of drugs or production of biomaterials for tissue regeneration. This study shows that the 1,3-β-d-glucan polymer sample gelled at 80 °C has a distinctly different structure than the matrix gelled at 90 °C.

Immobilization of oligonucleotide-functionalized magnetic nanobeads in DNA-coils studied by electron microscopy and atomic force microscopy

2011 ◽  
Vol 1355 ◽  
Author(s):  
Mattias Strömberg ◽  
Sultan Akhtar ◽  
Klas Gunnarsson ◽  
Camilla Russell ◽  
David Herthnek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Surface Coverage ◽  
Rolling Circle Amplification ◽  
High Surface ◽  
Rolling Circle ◽  
Force Microscopy ◽  
Atomic Force ◽  
Immobilized Beads ◽  
Magnetic Nanobeads

ABSTRACTImmobilization of oligonucleotide-functionalized magnetic nanobeads by hybridization in DNA-coils formed by rolling circle amplification has been investigated using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The TEM results supported earlier made observations that small beads with low oligonucleotide surface coverage preferably immobilize in the interior of the DNA-coils and do not tend to link several DNA-coils together whereas large beads with high surface coverage to a larger extent connect several DNA-coils together to clusters of several DNA-coils with beads. AFM provided direct visualization of the DNA-coils as thread-like objects. DNA-coils with immobilized beads appeared as a collection of beads with thread-like features in their near vicinity.

The effects of humidity and surface free energy on adhesion force between atomic force microscopy tip and a silane self-assembled monolayer film

2010 ◽  
Vol 25 (3) ◽  
pp. 556-562 ◽  
Author(s):  
Chien-Chao Huang ◽  
Lijiang Chen ◽  
Xiaohong Gu ◽  
Minhua Zhao ◽  
Tinh Nguyen ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Free Energy ◽  
Surface Free Energy ◽  
Adhesion Force ◽  
Capillary Condensation ◽  
Self Assembled Monolayer ◽  
Force Microscopy ◽  
Atomic Force ◽  
Rate Of Increase ◽  
Self Assembled

The relationship between atomic force microscopy probe-sample adhesion force and relative humidity (RH) at five different levels of surface free energy (γs) of an organic self-assembled monolayer (SAM) has been investigated. Different γs levels were achieved by exposing a patterned SiO2/CH3-terminated octyldimethylchlorosilane SAM sample to an ultraviolet (UV)/ozone atmosphere. A model consisting of the Laplace-Kelvin theory for capillary condensation for nanosized probe and probe-sample molecular interaction was derived to describe the adhesion force as a function of RH from 25 to 90% for different SAM γs values. The equations were solved analytically by using an equivalent curvature of the probe tip shape. Experimental results show that the adhesion force increases slightly with RH for nonpolar SAM. However, for polar SAM surfaces, it increases at first, reaches a maximum, and then decreases. Both the rate of increase and the maximum of the adhesion force with humidity are γs-dependent, which is in good agreement with theoretical prediction. The large rise in the adhesion force in this RH range is due to the capillary force.

scholarly journals Inkjet Printing of Controlled ZnO Nanoparticles Layering

2019 ◽  
Vol 8 (1) ◽  
pp. 34-40
Author(s):  
N. Spinella ◽  
C. Galati ◽  
L. Renna
Keyword(s):  
Zno Nanoparticles ◽  
Gas Sensing ◽  
High Surface ◽  
Volume Ratio ◽  
Specific Chemical ◽  
Force Microscopy ◽  
Electron Microscopies ◽  
Atomic Force ◽  
Preliminary Study

 Controlled layering of functional material can produced a versatile film with specific chemical and physical proprieties for desirable applications. This article presented inkjet multilayer structures of ZnO nanoparticles of specific layer morphology and thickness for the development of devices where a high surface-to-volume ratio is required (e.g. micro gas sensors). Stacked multilayers were stratified through a multi-run printing process suitable to produce large-square pattern on flat silicon support. The formation of a multilayer structure was demonstrate through an extended structural characterization of the resulting film. Printed layer morphology was investigated with optical and scanning electron microscopies; atomic force microscopy profiling characterizations were conducted over the entire printed area to evaluate the pattern reproducibility. Finally, a preliminary study as gas sensing film was performed, using the alcohol/ZnO interaction experiments.

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