Investigation of hydrocarbon-plasma-generated carbon films by electron-energy-loss spectroscopy

Fink, J.; Müller-Heinzerling, Th.; Pflüger, J.; Scheerer, B.; Dischler, B.; Koidl, P.; Bubenzer, A.; Sah, R. E.

doi:10.1103/physrevb.30.4713

Cited by 271 publications

(77 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This broad band results from σ +π excitations and is centred around 27.0 eV for samples prepared with wall temperatures of 100 and 80 • C and at a slightly lower energy of ∼25 eV for T wall = 60 • C. These loss features are typical of graphite-like structures, like carbon nanotubes [32][33][34]. Peaks at ∼6 eV are attributed to π -π* collective excitations.…”

Section: Xps Analysismentioning

confidence: 97%

Microwave plasmas applied for the synthesis of free standing graphene sheets

Tatarova¹,

Dias²,

Henriques³

et al. 2014

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Self-standing graphene sheets were synthesized using microwave plasmas driven by surface waves at 2.45 GHz stimulating frequency and atmospheric pressure. The method is based on injecting ethanol molecules through a microwave argon plasma environment, where decomposition of ethanol molecules takes place. The evolution of the ethanol decomposition was studied in situ by plasma emission spectroscopy. Free gas-phase carbon atoms created in the plasma diffuse into colder zones, both in radial and axial directions, and aggregate into solid carbon nuclei. The main part of the solid carbon is gradually withdrawn from the hot region of the plasma in the outlet plasma stream where nanostructures assemble and grow. Externally forced heating in the assembly zone of the plasma reactor has been applied to engineer the structural qualities of the assembled nanostructures. The synthesized graphene sheets have been analysed by Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy and x-ray photoelectron spectroscopy. The presence of sp 3 carbons is reduced by increasing the gas temperature in the assembly zone of the plasma reactor. As a general trend, the number of mono-layers decreases when the wall temperature increases from 60 to 100 • C. The synthesized graphene sheets are stable and highly ordered.

show abstract

Section: Xps Analysismentioning

confidence: 97%

Microwave plasmas applied for the synthesis of free standing graphene sheets

Tatarova¹,

Dias²,

Henriques³

et al. 2014

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…Infrared spectra of HAC deposited at low temperatures by plasma deposition show that the hydrogen content and bonding can be influenced by thermal and radiative interactions (Ogmen & Duley 1988;Duley 1994). In the laboratory, HAC is found to graphitize on heating (Wada, Gaczi, & Solin 1980;Smith 1984;Fink et al 1984;Grill, Patel, & Meyerson 1990). This occurs in a series of stages on heating to temperatures T ?…”

Section: Introductionmentioning

confidence: 99%

The Decomposition of Hydrogenated Amorphous Carbon: A Connection with Polycyclic Aromatic Hydrocarbon Molecules

Scott

Duley

1996

The Astrophysical Journal

View full text Add to dashboard Cite

We have produced thin solid films of hydrogenated amorphous carbon (HAC) by vapor deposition in vacuum and have investigated the structure and infrared spectra of these materials under conditions in which they are at the point of decomposition. We find that the IR absorption spectrum of HAC under these conditions contains all the major spectral components seen in emission in nebulae. In addition, high-resolution scanning tunneling microscopy of HAC prior to decomposition reveals protographitic islands with dimensions 11-5 nm showing that polycyclic aromatic hydrocarbon (PAH)-like molecular groups evolve from HAC. These experimental results suggest for the first time how PAHs and HAC may be related and how PAH molecules could evolve from HAC in regions of high excitation. The material produced as HAC decomposes is a very low density carbonaceous "aerogel" consisting primarily of these aromatic protographitic clusters in a weakly connected friable network. These protographitic clusters may be the source of interstellar graphite grains.

show abstract

“…Few laboratory based determinations of optical constants of carbon analogs exist for λ < 120 nm. Fink et al (1984) measured the EELS spectra from 300 nm to 40 nm for amorphous carbons. Colangeli et al (1993) measured the spectra of carbon samples down to ∼50 nm through transmission or reflection on a gold-coated quartz window.…”

Section: General Overviewmentioning

confidence: 99%

VUV spectroscopy of carbon dust analogs: contribution to interstellar extinction

Gavilan

Alata

et al. 2016

A&A

View full text Add to dashboard Cite

Context.A full spectral characterization of carbonaceous dust analogs is necessary to understand their potential as carriers of observed astronomical spectral signatures such as the ubiquitous UV bump at 217.5 nm and the far-ultraviolet (FUV) rise common to interstellar extinction curves. Aims. Our goal is to study the spectral properties of carbonaceous dust analogs from the FUV to the mid-infrared (MIR) domain. We seek in particular to understand the spectra of these materials in the FUV range, for which laboratory studies are scarce. Methods. We produced analogs to carbonaceous interstellar dust encountered in various phases of the interstellar medium: amorphous hydrogenated carbons (a-C:H), for carbonaceous dust observed in the diffuse interstellar medium, and soot particles, for the polyaromatic component. Analogs to a-C:H dust were produced using a radio-frequency plasma reactor at low pressures, and soot nanoparticles films were produced in an ethylene (C 2 H 4 ) flame. We measured transmission spectra of these thin films (thickness <100 nm) in the far-ultraviolet (190−250 nm) and in the vacuum-ultraviolet (VUV; 50−190 nm) regions using the APEX chamber at the DISCO beam line of the SOLEIL synchrotron radiation facility. These were also characterized through infrared microscopy at the SMIS beam line. Results. We successfully measured the transmission spectra of these analogs from λ = 1 μm to 50 nm. From these, we extracted the laboratory optical constants via Kramers-Kronig inversion. We used these constants for comparison to existing interstellar extinction curves. Conclusions. We extend the spectral measurements of these types of carbonaceous analogs into the VUV and link the spectral features in this range to the 3.4 μm band. We suggest that these two materials might contribute to different classes of interstellar extinction curves.

show abstract

Investigation of hydrocarbon-plasma-generated carbon films by electron-energy-loss spectroscopy

Cited by 271 publications

References 19 publications

Microwave plasmas applied for the synthesis of free standing graphene sheets

Microwave plasmas applied for the synthesis of free standing graphene sheets

The Decomposition of Hydrogenated Amorphous Carbon: A Connection with Polycyclic Aromatic Hydrocarbon Molecules

VUV spectroscopy of carbon dust analogs: contribution to interstellar extinction

Contact Info

Product

Resources

About