Search results for " Atomic Force"
showing 10 items of 172 documents
Adhesive interaction measured between AFM probe and lung epithelial type II cells
2007
The toxicity of inhaled nanoparticles entering the body through the lung is thought to be initially defined by the electrostatic and adhesive interaction of the particles with lung's wall. Here, we investigated the first step of the interaction of nanoparticles with lung epithelial cells using atomic force microscope (AFM) as a force apparatus. Nanoparticles were modeled by the apex of the AFM tip and the forces of interaction between the tip and the cell analyzed over time. The adhesive force and work of adhesion strongly increased for the first 100 s of contact and then leveled out. During this time, the tip was penetrating deeply into the cell. It first crossed a stiff region of the cell…
Sintering process of amorphous SiO2 nanoparticles investigated by AFM, IR and Raman techniques
2011
We report an experimental investigation on the effects of thermal treatments at different temperatures (room-1270 K) and for different duration (0-75 h) on amorphous silica nanoparticles (fumed silica) in powder tablet form. Three types of fumed silica are considered, comprising nearly spherical particles of 40 nm, 14 nm and 7 nm mean diameter. The experimental techniques used here are Raman and infrared absorption (IR) spectroscopy together with atomic force microscopy (AFM). Raman and IR spectra indicate that the structure of nanometer silica particles is significantly different with respect to that of a bulk silica glass. In particular, the main differences regard the positions of the IR…
Measurements of thickness dispersion in biolayers by scanning force microscopy and comparison with spectroscopic ellipsometry analysis.
2007
Measuring the thickness of biological films remains a difficult task when using differential measurements by atomic force microscopy (AFM). The use of microstructured substrates combined with a selective adsorption constitutes an alternative to tribological measurements. The statistical thickness analysis of biological layers, especially via the dispersion measurements, can provide a way to quantify the molecular orientation. AFM thicknesses were then compared with those obtained optically by spectroscopic ellipsometry (SE) and surface plasmon resonance enhanced ellipsometry (SPREE). The biolayers could then be modeled using a vertical gradient of optical index, which reflects height disper…
Spin-polarized scanning tunneling microscopy and spectroscopy of ultrathinFe∕Mo(110)films usingW∕Au∕Cotips
2006
We report on magnetic contrast observed in low-temperature spin-polarized scanning tunneling microscopy (SP-STM) of Fe nanowires deposited on Mo(110) using tungsten tips covered by $\mathrm{Au}∕\mathrm{Co}$ thin films. Due to the spin reorientation transition of Co films on Au an out-of-plane magnetic sensitivity is obtained for tips with thin cobalt films (up to 8 monolayers of Co), while for thicker Co coverages an in-plane magnetization component can be probed. Using $\mathrm{W}∕\mathrm{Au}∕\mathrm{Co}$ tips with out-of-plane magnetic sensitivity we show that the one (ML) and two (DL) atomic layers thick Fe nanowires prepared using step flow growth on a Mo(110) crystal are perpendicularl…
Synthesis and characterisation of ordered arrays of mesoporous carbon nanofibres
2009
A facile and reproducible one-step pathway has been developed for preparing ordered arrays of mesoporous carbon nanostructures within the pores of anodized aluminium oxide (AAO) membranes, through the confined self-assembly of phenol/formaldehyde resol and amphiphilic copolymer templates. The morphology of the mesoporous carbon nanostructures can be controlled by varying the copolymer surfactant, the quantity of the resol–surfactant precursor sol used and the amount of phenol–formaldehyde resol introduced into the resol–surfactant sol. One-dimensional (1-D) carbon nanostructures, such as carbon fibres with a core–shell structure and carbon ribbons with circular mesopores running parallel to…
Conductive films of ordered nanowire arrays
2004
peer-reviewed High-density, ordered arrays of germanium nanowires have been synthesised within the pores of mesoporous thin films (MTFs) and anodized aluminium oxide (AAO) matrices using a supercritical fluid solution-phase inclusion technique. Conductive atomic force microscopy (C-AFM) was utilised to study the electrical properties of the nanowires within these arrays. Nearly all of the semiconductor nanowires contained within the AAO substrates were found to be conducting. Additionally, each individual nanowire within the substrate possessed similar electrical properties demonstrating that the nanowires are continuous and reproducible within each pore. C-AFM was also able to probe the co…
Achieving high effectiveQ-factors in ultra-high vacuum dynamic force microscopy
2010
The effective Q-factor of the cantilever is one of the most important figures-of-merit for a non-contact atomic force microscope (NC-AFM) operated in ultra-high vacuum (UHV). We provide a comprehensive discussion of all effects influencing the Q-factor and compare measured Q-factors to results from simulations based on the dimensions of the cantilevers. We introduce a methodology to investigate in detail how the effective Q-factor depends on the fixation technique of the cantilever. Fixation loss is identified as a most important contribution in addition to the hitherto discussed effects and we describe a strategy for avoiding fixation loss and obtaining high effective Q-factors in the forc…
Perylenetetracarboxylic anhydride as a precursor of fluorescent carbon nanoonion rings
2015
[EN] Thermal annealing at 400 degrees C of perylenetetracarboxylic anhydride in low molecular mass PEG gives rise to the formation of well defined nanoobjects of 2.5 nm height and size distribution from 10 to 65 nm (average 40 nm) after purification of the raw mixture with silicagel chromatography. TEM reveals that the flat nanoobjects are constituted of concentric graphenic rings (0.34 nm interlayer distance). The morphology of the nanoparticles resembles onion rings of nanometric dimensions (nanoonion rings C-NOR). C-NOR particles have an excitation dependent emission with lambda(em) from 430 to 570 nm and a maximum emission quantum yield of 0.49. C-NOR particles can be internalized into …
Magneto-Optical Properties of Electrodeposited Thin Films of the Molecule-Based Magnet Cr5.5(CN)12·11.5H2O
2011
Prof. E. Coronado , M. Makarewicz , J. P. Prieto-Ruiz , Dr. H. Prima-Garcia , Dr. F. M. Romero Instituto de Ciencia Molecular (ICMol) Universitat de Valencia C/Catedratico Jose Beltran, 2, 46980-Paterna, Spain E-mail: eugenio.coronado@uv.es; helena.prima@uv.es; fmrm@uv.es
The Use of Atomic Force Microscopy in Determining the Stiffness and Adhesion Force of Human Dentin After Exposure to Bleaching Agents
2009
Introduction: Oxidant bleaching agents may induce several alterations on mineralized teeth tissues. Our aim is to study,at the ultrastructurallevel,mechanicalmodifications induced on dentin after exposure to different bleaching agents.Methods: Nanoindentation performed with atomic force microscopy was used to measure changes in dentin stiffness as well as the adhesion force between the tip and the tissue both in intertubular and peritubulardentin.Foreachspecimen,dentinlocalization, and bleaching agent, 100 independent nanoindentations were performed. Carbamide peroxide (30%) and hydrogenperoxide(35%) wereusedasbleaching agents. Results: A significant reduction of both stiffness and adhesion…