A5031218447- Force Microscopy Techniques and Applications
- Graphene research and applications
- Carbon Nanotubes in Composites
- Diamond and Carbon-based Materials Research
- Tribology and Wear Analysis
- Metal and Thin Film Mechanics
- Orthopaedic implants and arthroplasty
- Advanced Surface Polishing Techniques
- Ion-surface interactions and analysis
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced materials and composites
- Lubricants and Their Additives
- Carbon and Quantum Dots Applications
- Graphene and Nanomaterials Applications
- Quality and Safety in Healthcare
- Data Visualization and Analytics
- Vascular anomalies and interventions
- Surface and Thin Film Phenomena
- Metal Alloys Wear and Properties
- Plasmonic and Surface Plasmon Research
- Explainable Artificial Intelligence (XAI)
- Advanced Nanomaterials in Catalysis
- Anomaly Detection Techniques and Applications
Instituto Nacional de Metrologia, Qualidade e Tecnologia
2014-2025
University of California, Santa Cruz
2024
Argonne National Laboratory
2024
Centro Hospitalar de Vila Nova de Gaia
2020-2023
Pontifical Catholic University of Rio de Janeiro
2008-2010
When two identical two-dimensional periodic structures are superposed, a mismatch rotation angle between the generates superlattice. This effect is commonly observed in graphite, where graphene layers Moiré patterns scanning tunneling microscopy images. Here, study of intravalley and intervalley double-resonance Raman processes mediated by static potentials rotationally stacked bilayer presented. The peak properties depend on can be used as an optical signature for superlattices graphene. An...
In this work, a study of resonance effects in the Raman spectra twisted bilayer graphene (tBLG) is presented. The analysis takes into account effect mismatch angle $\ensuremath{\theta}$ between two layers, and also excitation laser energy on frequency, linewidth, intensity main features, namely rotationally induced $R$ band, $G$ second-order ${G}^{\ensuremath{'}}$ (or $2D$) band. are explained based dependence tBLG electronic structure, as calculated by ab initio methodologies. twist defines...
Abstract The nanoscale friction between an atomic force microscopy tip and graphene is investigated using (FFM). During the movement, forces are observed to increase then saturate in a highly anisotropic manner. As result, dependent on scanning direction: under some conditions, energy dissipated along armchair direction can be 80% higher than zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), anisotropy directions only 15%. This giant results from anisotropies...
Bacterial infections associated with healthcare are a challenge on global scale due to the high morbidity and mortality rates, especially those caused by multidrug-resistant isolates. Hospital textiles abiotic surfaces that may serve as means of disseminating persisting microorganisms in hospitals, can remain viable these for up months. In this study, we employed green synthesis approach utilizing guava leaf extract (Psidium guajava) produce silver nanoparticles, which were then incorporated...
In this work, we clarify the features of lateral damage line defects in single layer graphene. The were produced through well-controlled etching graphene using a Ga+ focused ion beam. length was obtained from both integrated intensity disorder induced Raman D band and minimum fluence. Also, characterized by polarized spectroscopy. It found that is resilient under conditions since defect peak exhibits dependence on direction lines relative to crystalline lattice also laser polarization lines....
In this work, an endogenous self-doping N,P,S-CQDs was synthesized by the acid hydrolysis of pumpkin seeds (Cucurbita maxima) and its performance as a corrosion inhibitor evaluated. Mild steel (MS) is one most used materials in industry; however, it has low resistance acidic environments. Pumpkin cultivated worldwide, compositional characteristic makes great alternative raw material to produce CQDs. The results show that CQD successfully obtained with size distribution smaller than 10 nm....
Abstract During the past years, great effort has been made to improve tribological performance of ultra‐high molecular weight polyethylene (UHMWPE), considered a key polymeric material in applications requiring elevated mechanical and corrosion resistance bioinertness. This work aimed investigate role adding ceramic nanofillers aluminum oxide (Al 2 O 3 ) boron carbide (B 4 C) UHMWPE matrix order modify triboperformance polymer. The results obtained through dry reciprocating sliding tests up...
Abstract The influence of sliding speed in the nanoscale friction forces between a silicon tip and monolayer multilayer graphene were investigated with use an atomic force microscope. We found that increase linearly logarithm highly layer-dependent way. velocity is amplified at monolayer. amplification results from introduction additional corrugation interaction potential driven by movement. This effect can be interpreted as manifestation local thermally induced surface corrugations...
Flake thickness is one of the defining properties graphene-related 2D materials (GR2Ms), and therefore requires reliable, accurate, reproducible measurements with well-understood uncertainties. This needed regardless production method or manufacturer because it important for all GR2M products to be globally comparable. An international interlaboratory comparison on graphene oxide flakes using atomic force microscopy has been completed in technical working area 41 versailles project advanced...
The direct determination of the crystallographic orientation graphene sheets was performed using lattice resolution atomic force microscopy images. A sample, micromechanically exfoliated onto a SiO2 substrate showing well defined crystal edges, imaged in lateral mode. images reveal periodicity hexagonal structure allowing visualization symmetries and orientation. Crystal edges predominantly formed by zigzag or armchair directions were identified. nature confirmed Raman spectroscopy.
Exposure to ambient air contaminates the surface of graphene sheets. Contamination may arise from different sources, and its nature alters frictional behavior material. These changes in friction enable observation early stages contaminants’ adsorption graphene. Using a force microscope, we show that molecular initiates at edges mechanical defects monolayer. Once monolayer is covered, contaminants spread over additional layers. With this method, estimate contamination kinetics. In graphene,...
Abstract The optical field generated by a nanoplasmonic probe is revealed in tip-enhanced Raman spectroscopy (TERS) experiments. TERS intensity profile of nano-objects smaller than the probe’s apex has donut-like shape which resembles magnitude point-dipole source, being well described Dyadic Green’s function. Having prior knowledge on excitation probe, we measured width shear solitons caused lattice reconstruction low-angle twisted bilayer graphene, prominent platform for twistronics, and...
The nature of nanoscratching as a lithographic technique for site-selective generation dislocations is investigated use in the growth nanostructures. Linear arrays have been selectively introduced into (001) indium phosphide crystals by dragging diamond tip an atomic force microscope. plastic deformation found to depend on scratch direction. For ⟨110⟩ directions, anisotropic butterflylike structures with mostly screw indicate rotational motion vicinity advancing tip. ⟨100⟩ do not propagate...
Nanoindentations were performed on a cubic semiconductor using cono-spherical diamond tip with 260 nm radius. The produces single point of contact the crystal surface allowing indentations nano-scale dimensions. early stages deformation (100) InP zinc-blende structure observed to happen by sequential introduction metastable dislocation loops along various slip planes directly beneath contact. Locking dislocations forms hardened region that acts as an extended during subsequent indentation,...
Native oxide has been found to have a noticeable effect on the mechanical deformation of InP during nanoindentation. The indentations were performed using spherical diamond tips and residual impressions studied by atomic force microscopy. It observed that in early stages deformation, plastic flow occurs layer while indium phosphide is still elastic regime. deformed native results pile-up formation causes an increase contact area between tip surface nanoindentation process. This projected...
The microstructure of (001) InP crystals scratched with a sharp diamond tip depends strongly on the scratching direction. scratch surface is found to conform radius curvature (∼60 nm) by formation atomic crystal steps produced dislocation glide along {111} planes. ⟨110⟩ scratches lead coherent local lattice movement and rotation causing deep propagation into irregular pileups at sides surface. ⟨100⟩ incoherent locking that inhibits their results in regular pileups.
Linear arrays of InAs nanocrystals have been produced by metalorganic vapor phase epitaxy on scratches performed with an atomic force microscope tip along specific crystallographic directions (100) InP wafer. Scratches ⟨110⟩ generate highly mobile defects that extend far from the scratch region easy-glide directions. On other hand, ⟨100⟩ result in highly-localized plastic deformation, hardening, and possibly frictional heating. In both cases, growth was observed only scratched areas. Random...
The effect of scratch proximity on the resistance to plastic deformation in InP (100) crystals under low normal loads has been studied using atomic force microscopy (AFM) and transmission electron microscopy. Plastic flow observed for scratches performed with an microscope along ⟨110⟩ ⟨100⟩ crystallographic directions. hardening determined from AFM measurements depth width, as a function distance between parallel scratches. For relatively loads, is found be independent direction scratch....
Carbon-derived compounds are gaining traction in the scientific community because of their unique properties, such as conductivity and strength, promising innovations technology medicine.