Possible effect of carbon nanotube diameter on gas–surface interactions – The case of benzene, water, and n-pentane adsorption on SWCNTs at ultra-high vacuum conditions

2009 ◽  
Vol 476 (4-6) ◽  
pp. 227-231 ◽  
Author(s):  
M. Komarneni ◽  
A. Sand ◽  
J. Goering ◽  
U. Burghaus ◽  
M. Lu ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
High Vacuum ◽  
Surface Interactions ◽  
Ultra High Vacuum ◽  
Gas Surface Interactions

Synthesis of carbon nanotube/TiO2 composites by titanium evaporation in ultra high vacuum ambient

2013 ◽  
Vol 108 ◽  
pp. 213-217 ◽  
Author(s):  
M. Barberio ◽  
V. Pingitore ◽  
P. Barone ◽  
M. Davoli ◽  
F. Stranges ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
High Vacuum ◽  
Ultra High Vacuum

Ion-Surface Interactions During Epitaxy

1990 ◽  
Vol 201 ◽  
Author(s):  
S. A. Barnett ◽  
C.-H. Choi ◽  
R. Kaspi
Keyword(s):  
High Vacuum ◽  
Surface Interactions ◽  
Epitaxial Films ◽  
Ultra High Vacuum ◽  
Semiconductor Materials ◽  
Layer By Layer ◽  
Crystalline Perfection ◽  
Ion Energies ◽  
Miscibility Gaps ◽  
Deposition Techniques

AbstractRecent work on low-energy ion-assisted deposition of epitaxial films is reviewed. Much of the interest in this area has centered on the use of very low ion energies (∼ 25 eV) and high fluxes (> 1 ion per deposited atom) obtained using novel ion-assisted deposition techniques. These methods have been applied in ultra-high vacuum, allowing the preparation of high-purity semiconductor materials. The following ion-surface interaction effects during epitaxy are discussed: improvements in crystalline perfection during low temperature epitaxy, ion damage effects, improved homogeneity and properties in III-V alloys grown within miscibility gaps, and changes in nucleation mechanism from Stranski-Krastanov to layer-by-layer.

scholarly journals Impact of Surface Roughness on Ion-Surface Interactions Studied with Energetic Carbon Ions 13C+ on Tungsten Surfaces

2019 ◽  
Vol 4 (1) ◽  
pp. 29 ◽  
Author(s):  
Maren Hellwig ◽  
Martin Köppen ◽  
Albert Hiller ◽  
Hans Koslowski ◽  
Andrey Litnovsky ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Angular Distribution ◽  
Surface Morphology ◽  
High Vacuum ◽  
Surface Interactions ◽  
Surface Interaction ◽  
Ultra High Vacuum ◽  
Nuclear Reaction Analysis ◽  
Angle Of Incidence ◽  
Carbon Ions

The effect of surface roughness on angular distributions of reflected and physically sputtered particles is investigated by ultra-high vacuum (UHV) ion-surface interaction experiments. For this purpose, a smooth (R a = 5.9 nm) and a rough (R a = 20.5 nm) tungsten (W) surface were bombarded with carbon ions 13C+ under incidence angles of 30 ∘ and 80 ∘ . Reflected and sputtered particles were collected on foils to measure the resulting angular distribution as a function of surface morphology. For the qualitative and quantitative analysis, secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) were performed. Simulations of ion-surface interactions were carried out with the SDTrimSP (Static Dynamic Transport of Ions in Matter Sputtering) code. For rough surfaces, a special routine was derived and implemented. Experimental as well as calculated results prove a significant impact of surface roughness on the angular distribution of reflected and sputtered particles. It is demonstrated that the effective sticking of C on W is a function of the angle of incidence and surface morphology. It is found that the predominant ion-surface interaction process changes with fluence.

scholarly journals Hydrogen Nanometrology in Advanced Carbon Nanomaterial Electrodes

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1079
Author(s):  
Rui Lobo ◽  
Noe Alvarez ◽  
Vesselin Shanov
Keyword(s):  
Carbon Nanotube ◽  
Hydrogen Storage ◽  
Hydrogen Adsorption ◽  
Accurate Determination ◽  
High Vacuum ◽  
Hydrogen Uptake ◽  
Ultra High Vacuum ◽  
3D Graphene ◽  
Hydrogen Mass ◽  
Carbon Nanotube Networks

A comparative experimental study between advanced carbon nanostructured electrodes, in similar hydrogen uptake/desorption conditions, is investigated making use of the recent molecular beam-thermal desorption spectrometry. This technique is used for monitoring hydrogen uptake and release from different carbon electrocatalysts: 3D-graphene, single-walled carbon nanotube networks, multi-walled carbon nanotube networks, and carbon nanotube thread. It allows an accurate determination of the hydrogen mass absorbed in electrodes made from these materials, with significant enhancement in the signal-to-noise ratio for trace hydrogen avoiding recourse to ultra-high vacuum procedures. The hydrogen mass spectra account for the enhanced surface capability for hydrogen adsorption in the different types of electrode in similar uptake conditions, and confirm their enhanced hydrogen storage capacity, pointing to a great potential of carbon nanotube threads in replacing the heavier metals or metal alloys as hydrogen storage media.

Fabrication of High-Density Carbon-Nanotube Coatings on Microstructured Substrates

2000 ◽  
Vol 621 ◽  
Author(s):  
Zheng Chen ◽  
Yonhua Tzeng ◽  
Chao Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Active Surface ◽  
Deposition Process ◽  
Ultra High Vacuum ◽  
Active Surface Area ◽  
Field Emission Properties ◽  
Ni Substrate

ABSTRACTFabrication and characterization of carbon nanotubes deposited on microstructured Ni substrate are presented. The highly active surface-area of the microstructured Ni substrate provides highdensity nucleation sites for carbon nanotubes. Coated fine Ni powder also serves as a catalyst for the nanotube growth. Hydrocarbon mixtures were used as the carbon source for the chemical vapor deposition process. Carbon nanotubes deposited on the microstructured Ni substrate were examined by SEM. An ultra high vacuum chamber was used to characterize the field emission properties of carbon nanotube coatings.

Growth of Carbon Nanotubes on Copper Substrates Using a Nickel Thin Film Catalyst

2009 ◽  
Vol 1204 ◽  
Author(s):  
Gowtam Atthipalli ◽  
Prashant Kumta ◽  
Wei Wang ◽  
Rigved Epur ◽  
Prashanth H Jampani ◽  
...  
Keyword(s):  
Thin Film ◽  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Nickel Catalyst ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Thin Film Catalyst ◽  
Carbon Nanotube Growth ◽  
Nanotube Growth

AbstractCarbon nanotubes with their attractive properties, one-dimensional character, and their large aspect ratio are ideal candidates for a variety of applications including energy storage, sensing, nanoelectronics, among others. We have studied the growth of carbon nanotubes on copper substrates using a nickel thin film as a catalyst. The catalyst was sputtered in a chamber having a base pressure in the ultra-high-vacuum regime. By adjusting the sputtering parameters, the effects of the morphology and the thickness of the nickel catalyst on the growth of carbon nanotubes have also been investigated. Multiple hydrocarbon sources as carbon feedstock (methane, acetylene and xylene) and corresponding catalyst precursors and varying temperature conditions were used during the Chemical Vapor Deposition (CVD) process to understand and best determine the ideal conditions for carbon nanotube growth on copper. Correlation between the thickness of the thin film nickel catalyst and the carbon nanotube diameter is also presented in the study. Characterization techniques used to study the morphology of the CNTs grown on copper include SEM, TEM and HRTEM, Raman Spectroscopy

Carbon Nanotube Modification Using BaF2 Vapor in Ultra-High Vacuum Environment

2003 ◽  
Vol 782 ◽  
Author(s):  
Francisco Santiago ◽  
Victor H. Gehman ◽  
Karen Long ◽  
Kevin A. Boulais
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Heat Exposure ◽  
Major Change ◽  
Ultra High Vacuum ◽  
Force Microscopy ◽  
Before And After ◽  
Potential Applications

ABSTRACTCarbon nanotubes have attracted significant attention in the scientific community due to their unique properties and potential applications. One of the most promising applications is a carbon-nanotube transistor. The motivation of this work is to find ways to connect carbon nanotubes directly to silicon using Ba as a chemical link. We studied chemical interactions between carbon nanotubes and BaF2 vapors using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Surfaces of silicon wafers were chemically modified to allow the epitaxial growth of BaF2 using molecular beam epitaxy (MBE). Samples containing 2D single crystal islands of BaF2 were covered with carbon nanotubes with an average coverage of 10 nanotubes per um2. The samples were transferred to an outgasing station inside the MBE system and heated to 900°C for two hours in a pressure of 10-9 mbar. XPS C1s data before and after heat show a major change in the nature of the carbon nanotube electronic states. In addition XPS shows formation of a Ba-C “carbide like” bond and no presence of fluorine. AFM images of the same region taken before and after heat exposure show remarkable changes in the surface morphology of the carbon-nanotube wall.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

Sign in / Sign up

Export Citation Format

Share Document