Spectroscopic Characterization of Flame-Generated 2-D Carbon Nano-Disks

2015 ◽  
Vol 1726 ◽  
Author(s):  
Patrizia Minutolo ◽  
Mario Commodo ◽  
Gianluigi De Falco ◽  
Rosanna Larciprete ◽  
Andrea D'Anna
Keyword(s):  
Carbon Nanostructures ◽  
Functional Materials ◽  
Building Blocks ◽  
Spectroscopic Characterization ◽  
Molecular Compound ◽  
Force Microscopy ◽  
Atomic Force ◽  
Thin Carbon ◽  
On Line ◽  
20 Nm

ABSTRACTIn this work we produce atomically thin carbon nanostructures which have a disk-like shape when deposited on a substrate. These nanostructures have intermediate characteristics between a graphene island and a molecular compound and have the potentiality to be used either as they are, or to become building blocks for functional materials or to be manipulated and engineered into composite layered structures.The carbon nanostructures are produced in a premixed ethylene/air flame with a slight excess of fuel with respect to the stoichiometric value. The size distribution of the produced compounds in aerosol phase has been measured on line by means of a differential mobility analyzer (DMA) and topographic images of the structures deposited on mica disks were obtained by Atomic Force Microscopy. Raman spectroscopy and XPS have been used to characterize their structure and the electronic and optical properties were obtained combining on-line photoionization measurements with Cyclic Voltammetry, light absorption and photoluminescence.When deposited on the mica substrate the carbon compounds assume the shape of an atomically thin disk with in plane diameter of about 20 nm. Carbon nano-disks consist of a network of small aromatic island with in plane length, La, of about 1 nm. Raman spectra evidence a significant amount of disorder which is in a large part due to the quantum confinement in the aromatic islands. Nano-disks contain small percentage of sp3 and the O/C ratio is lower than 6%. They furthermore present interesting UV and visible photoluminescence properties.

Double-layered Structure of Surface Modification of Low-k Dielectrics Induced by He Plasma

2005 ◽  
Vol 863 ◽  
Author(s):  
Ken-Ichi Yanai ◽  
Tadayoshi Hasebe ◽  
Kouji Sumiya ◽  
Seiki Oguni ◽  
Kazuhiro Koga
Keyword(s):  
Surface Modification ◽  
Layered Structure ◽  
Photoelectron Spectroscopy ◽  
Etch Depth ◽  
Force Microscopy ◽  
Atomic Force ◽  
Thin Carbon ◽  
Modified Surface ◽  
Almost All ◽  
20 Nm

AbstractSurface modification of a p-SiOC film induced by Helium (He) plasma was investigated using various measurements. Differential Fourier transform infrared absorption (FT-IR) spectra and the etch-depth measurements with the immersion in the mixed hydrofluoric acid (HF) indicate that the almost all of Si-CH3 bonds are broken in the modification layer, resulting in carbon-depletion, an SiO2-like composition. The x-ray photoelectron spectroscopy (XPS) measurements at different take-off angles reveal that the modified surface forms a double-layered structure, a thin carbon-rich top layer (about 1 nm thick) on a thick carbon-depletion layer (about 20 nm thick) with the irradiation of He plasma over 300 W. Atomic force microscopy (AFM) observations show that the modified surface is the smoothest in the case of the carbon-depletion surface.

ATOMIC FORCE MICROSCOPY AND XRD ANALYSIS OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2006 ◽  
Vol 20 (02) ◽  
pp. 217-231 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Thickness of the films varied between 20 nm and 72.8 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. Three-dimension and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching 41.9 nm when the film size reaches 60 nm. Grain size was calculated from the information provided by the XRD spectrum and averaging method. We could not find any sequential variation in the grain size with the growth rate.

scholarly journals Subwavelength hole arrays with nanoapertures fabricated by scanning probe nanolithography

2006 ◽  
Vol 38 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Z. Jaksic ◽  
M. Maksimovic ◽  
D. Vasiljevic-Radovic ◽  
M. Sarajlic
Keyword(s):  
Building Blocks ◽  
Scanning Probe ◽  
Positive Photoresist ◽  
Force Microscopy ◽  
Atomic Force ◽  
Optical Effects ◽  
Different Shapes ◽  
Subwavelength Hole Arrays ◽  
Hole Arrays ◽  
Electromagnetic Transmission

Owing to their surface plasmon-based operation, arrays of subwavelength holes show extraordinary electromagnetic transmission and intense field localizations of several orders of magnitude. Thus they were proposed as the basic building blocks for a number of applications utilizing the enhancement of nonlinear optical effects. We designed and simulated nanometer-sized subwavelength holes using an analytical approach. In our experiments we used the scanning probe method for nanolithographic fabrication of subwavelength hole arrays in silver layers sputtered on a positive photoresist substrate. We fabricated ordered nanohole patterns with different shapes, dispositions and proportions. The smallest width was about 60 nm. We characterized the fabricated samples by atomic force microscopy.

scholarly journals Layer by Layer Antimicrobial Coatings Based on Nafion, Lysozyme, and Chitosan

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1563 ◽  
Author(s):  
Ella N. Gibbons ◽  
Charis Winder ◽  
Elliot Barron ◽  
Diogo Fernandes ◽  
Marta J. Krysmann ◽  
...  
Keyword(s):  
Surface Characteristics ◽  
Building Blocks ◽  
Layer By Layer ◽  
Exclusion Zone ◽  
Antimicrobial Coatings ◽  
Force Microscopy ◽  
New Family ◽  
Atomic Force ◽  
Multilayer Assemblies ◽  
And Staphylococcus Aureus

The study focuses on the development of a new family of layer-by-layer coatings comprising Nafion, lysozyme and chitosan to address challenges related to microbial contamination. Circular dichroism was employed to gain insights on the interactions of the building blocks at the molecular level. Quartz crystal microbalance tests were used to monitor in real time the build-up of multilayer coatings, while atomic force microscopy, contact angle and surface zeta potential measurements were performed to assess the surface characteristics of the multilayer assemblies. Remarkably, the nanocoated surfaces show almost 100% reduction in the population of both Escherichia coli and Staphylococcus aureus. The study suggests that Nafion based synergistic platforms can offer an effective line of defence against bacteria, facilitating antimicrobial mechanisms that go beyond the concept of exclusion zone.

scholarly journals Structural and Chemical Hierarchy in Hydroxyapatite Coatings

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4447
Author(s):  
Karlis A. Gross ◽  
Christiane Petzold ◽  
Liene Pluduma-LaFarge ◽  
Maris Kumermanis ◽  
Håvard J. Haugen
Keyword(s):  
Electrical Potential ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Kelvin Probe ◽  
Structural Variations ◽  
Homogeneous Microstructure ◽  
Structural Hierarchy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hydroxyapatite Coatings

Hydroxyapatite coatings need similarly shaped splats as building blocks and then a homogeneous microstructure to unravel the structural and chemical hierarchy for more refined improvements to implant surfaces. Coatings were thermally sprayed with differently sized powders (20–40, 40–63 and 63–80 µm) to produce flattened homogeneous splats. The surface was characterized for splat shape by profilometry and Atomic force microscopy (AFM), crystal size by AFM, crystal orientation by X-ray diffraction (XRD) and structural variations by XRD. Chemical composition was assessed by phase analysis, but variations in chemistry were detected by XRD and Raman spectroscopy. The resulting surface electrical potential was measured by Kelvin probe AFM. Five levels of structural hierarchy were suggested: the coating, the splat, oriented crystals, alternate layers of oxyapatite and hydroxyapatite (HAp) and the suggested anion orientation. Chemical hierarchy was present over a lower range of order for smaller splats. Coatings made from smaller splats exhibited a greater electrical potential, inferred to arise from oxyapatite, and supplemented by ordered OH− ions in a rehydroxylated surface layer. A model has been proposed to show the influence of structural hierarchy on the electrical surface potential. Structural hierarchy is proposed as a means to further refine the properties of implant surfaces.

Characterization and Optimization of The Tco/a-Si:H(,B) Interface for Solar Cells by In-Situ Ellipsometry and Sims/XPS Depth Profiling

1994 ◽  
Vol 336 ◽  
Author(s):  
H.N. Wanka ◽  
E. Lotter ◽  
M.B. Schubert
Keyword(s):  
Solar Cells ◽  
Light Trapping ◽  
Hydrogen Plasma ◽  
Depth Profiling ◽  
Trapping Efficiency ◽  
Force Microscopy ◽  
Hydrogen Plasmas ◽  
Atomic Force ◽  
20 Nm

ABSTRACTThe chemical reactions at the surface of transparent conductive oxides (SnO2, ITO and ZnO) have been studied in silane and hydrogen plasmas by in-situ ellipsometry and by SIMS as well as XPS depth profiling. SIMS and XPS of the interface reveal an increasing amount of metallic phases upon lowering a-Si:H growth rates (controlled by plasma power), indicating that the ion and radical impact is more than compensated by protecting the surface by a rapidly growing a-Si:H film. Hence, optical transmission of TCO films as well as the efficiency of solar cells can be improved if the first few nanometers of the p-layer are grown at higher rates. Comparing a-Si:H deposition on top of different TCOs, reduction effects on ITO and SnO2 have been detected whereas ZnO appeared to be chemically stable. Therefore an additional shielding of the SnO2 surface by a thin ZnO layer has been investigated in greater detail. Small amounts of H are detected close to the ZnO surface by SIMS after hydrogen plasma treatment, but no significant changes occur to the optical and electrical properties. In-situ ellipsometry indicates that a ZnO layer as thin as 20 nm completely protects SnO2 from being reduced to metallic phases. This provides for shielding of textured TCOs, and hence rising solar cell efficiencies, too. Regarding light trapping efficiency we additionally investigated the smoothing of initial TCO texture when growing a-Si:H on top by combining atomic force microscopy and spectroscopie ellipsometry.

Photoconductive NSOM for mapping optoelectronic phases in nanostructures

Nanophotonics ◽  
2014 ◽  
Vol 3 (1-2) ◽  
pp. 19-31 ◽  
Author(s):  
Anshuman J. Das ◽  
Ravichandran Shivanna ◽  
K.S. Narayan
Keyword(s):  
Near Field ◽  
Functional Materials ◽  
Scanning Microscopy ◽  
Local Excitation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Local Current ◽  
Scanning Optical Microscopy ◽  
Microscopy Techniques ◽  
Current Monitoring

AbstractThe advent of optically functional materials with low-intensive processing methods is accompanied by a growing need for high resolution imaging to probe the inherent inhomogeneities in the underlying microstructure. Atomic force microscopy based techniques are typically utilized for imaging the surface of organic thin films, quantum dots and other nanomaterials with ultrahigh resolution. Several modes like conductive, Kelvin, electrostatic amongst others have been particularly successful in imaging the local current, potential and charge distribution of variety of systems. However, the functionality of photoconduction in these materials cannot be directly imaged by these modes alone. There is a requirement for a local excitation source or collection arrangement that is compatible with scanning microscopy techniques followed by a current monitoring mechanism. Near-field scanning optical microscopy (NSOM) possesses all the advantages of scanning microscopy and is capable of local excitation that overcomes the diffraction limit faced by conventional optical microscopes. Additionally, NSOM can be carried out on actual photoconductive two terminal and three terminal device structures to image local optoelectronic properties. In this review, we present the various geometries that have been demonstrated to perform photoconductive NSOM (p-NSOM). We highlight a representative set of important results and discuss the implications of photocurrent imaging in macroscopic device performance.

SURFACE PLASMON ENHANCED OPTICAL SECOND HARMONIC GENERATION IN ULTRA-THIN METALLIC FILMS

1999 ◽  
Vol 08 (04) ◽  
pp. 503-518 ◽  
Author(s):  
JUH-TZENG LUE ◽  
CHIA-SHY CHANG
Keyword(s):  
Second Harmonic ◽  
Angular Position ◽  
Field Enhancement ◽  
Surface Scattering ◽  
Metallic Films ◽  
Silver Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Peak Intensity ◽  
20 Nm

Internal reflection of second-harmonic generations from silver films with thickness ranging from 5 nm to 50 nm are enhanced by the excitation of surface plasmons under Kretschmann configuration. Enhancement of the SHG was observed at a film thickness of 20 nm resulting from the field enhancement of granular structure. For thinner films, the surface reveals disconnected islands as inspected by the atomic force microscopy. The incident angular position to find the peak intensity and the change of linewidth of the SHG can almost satisfactorily be predicted by the theory based on surface scattering.

Mechanical Stress, Grain-boundary Relaxation, and Oxidation of Sputtered CuNi(Mn) Films

1999 ◽  
Vol 14 (4) ◽  
pp. 1286-1294 ◽  
Author(s):  
W. Brückner ◽  
W. Pitschke ◽  
S. Baunack ◽  
J. Thomas
Keyword(s):  
Grain Boundary ◽  
Microstructural Characterization ◽  
Excess Vacancy ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Boundary Relaxation ◽  
20 Nm ◽  
Atomic Rearrangement

This paper focuses on understanding stress development in CuNi42Mn1 thin films during annealing in Ar. In addition to stress-temperature measurements, resistance-temperature investigations and chemical and microstructural characterization by Auger electron spectroscopy, scanning and transmission electron microscopy, x-ray diffraction, and atomic force microscopy were also carried out. The films are polycrystalline with a grain size of 20 nm up to 450 °C. To explain the stress evolution above 120 °C, atomic rearrangement (excess-vacancy annihilation, grain-boundary relaxation, and shrinkage of grain-boundary voids) and oxidation were considered. Grain-boundary relaxation was found to be the dominating process up to 250–300 °C. A sharp transition from compressive to tensile stress between 300 and 380 °C is explained by the formation of a NiO surface layer due to reaction with the remaining oxygen in the Ar atmosphere. This oxidation is masking the inherent structural relaxation above 300 °C.

Diameter-Selective Solubilization of Carbon Nanotubes by Lipid Micelles

2008 ◽  
Vol 8 (1) ◽  
pp. 420-423 ◽  
Author(s):  
Dimitrios Tasis ◽  
Konstantinos Papagelis ◽  
Dionysios Douroumis ◽  
James R. Smith ◽  
Nikolaos Bouropoulos ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanostructures ◽  
Aqueous Suspension ◽  
Aqueous Media ◽  
Microscopy Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
One Step ◽  
The One ◽  
Walled Carbon Nanotubes

The one-step dispersion of HiPco single-walled carbon nanotubes in aqueous media with the use of a synthetic lyso-phosphatidylcholine was studied. Solubilization occurs through wrapping of lipid molecules around the circumference of the tubes, yielding lipid monolayers on the graphitic sidewalls as evidenced by atomic force microscopy imaging and dynamic light scattering measurements. Raman spectroscopy showed that the dispersion and centrifugation process leads to an effective enrichment of the stable aqueous suspension in carbon nanostructures with smaller diameters.

Sign in / Sign up

Export Citation Format

Share Document