Plasma polymerization chemistry of unsaturated hydrocarbons: Neutral species identification by mass spectrometry

Résultats de recherche: Contribution à un journal/une revueArticle

Résumé

Radio frequency discharges ignited in low-pressure and pure hydrocarbon gases were investigated by mass spectrometry. The plasma process was applied to four unsaturated monomers: styrene C8H8, benzene C 6H 6, ethylene C2H 4 and acetylene C2H 2. The remote mass spectrometer location restricted species identification to neutral closed-shell molecules in their respective plasmas. Among the peaks in the mass spectra, those directly due to neutrals produced in the plasma were determined following a successful two-step methodology. Firstly, the use of low electron impact energy limited the fragmentation and strongly simplified the cracking patterns. Secondly, attribution of peaks directly due to neutrals was confirmed or ruled out by systematically measuring their appearance potential. In the case of styrene, not less than 48 new molecules were detected. The discussion of the observed stable by-products in each discharge suggested several radicals responsible for their production. Comparing the set of species among the four plasmas showed that the repeated addition of intermediates with one or two carbon atoms and with low H content dominated the chemistry. Under our conditions of intermediate to high W/FM (power over mass flow ratio), the gas-phase plasma polymerization then preferentially occurred through significant fragmentation and recombination. Finally, the measured appearance potentials during plasma provided estimation for the threshold ionization energy of several highly unsaturated hydrocarbons, useful for modeling.

langue originaleAnglais
Numéro d'article045010
Nombre de pages14
journalPlasma Sources Science and Technology
Volume23
Numéro de publication4
Les DOIs
étatPublié - 1 août 2014

Empreinte digitale

mass spectroscopy
polymerization
hydrocarbons
chemistry
styrenes
fragmentation
radio frequency discharge
plasma potentials
mass flow
acetylene
frequency modulation
mass spectrometers
mass spectra
electron impact
molecules
ethylene
low pressure
monomers
benzene
methodology

Citer ceci

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title = "Plasma polymerization chemistry of unsaturated hydrocarbons: Neutral species identification by mass spectrometry",
abstract = "Radio frequency discharges ignited in low-pressure and pure hydrocarbon gases were investigated by mass spectrometry. The plasma process was applied to four unsaturated monomers: styrene C8H8, benzene C 6H 6, ethylene C2H 4 and acetylene C2H 2. The remote mass spectrometer location restricted species identification to neutral closed-shell molecules in their respective plasmas. Among the peaks in the mass spectra, those directly due to neutrals produced in the plasma were determined following a successful two-step methodology. Firstly, the use of low electron impact energy limited the fragmentation and strongly simplified the cracking patterns. Secondly, attribution of peaks directly due to neutrals was confirmed or ruled out by systematically measuring their appearance potential. In the case of styrene, not less than 48 new molecules were detected. The discussion of the observed stable by-products in each discharge suggested several radicals responsible for their production. Comparing the set of species among the four plasmas showed that the repeated addition of intermediates with one or two carbon atoms and with low H content dominated the chemistry. Under our conditions of intermediate to high W/FM (power over mass flow ratio), the gas-phase plasma polymerization then preferentially occurred through significant fragmentation and recombination. Finally, the measured appearance potentials during plasma provided estimation for the threshold ionization energy of several highly unsaturated hydrocarbons, useful for modeling.",
keywords = "acetylene, benzene, ethylene, mass spectrometry, plasma chemistry, plasma polymerization, styrene",
author = "Xavier Gillon and L. Houssiau",
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Plasma polymerization chemistry of unsaturated hydrocarbons: Neutral species identification by mass spectrometry. / Gillon, Xavier; Houssiau, L.

Dans: Plasma Sources Science and Technology, Vol 23, Numéro 4, 045010, 01.08.2014.

Résultats de recherche: Contribution à un journal/une revueArticle

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AU - Gillon, Xavier

AU - Houssiau, L.

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N2 - Radio frequency discharges ignited in low-pressure and pure hydrocarbon gases were investigated by mass spectrometry. The plasma process was applied to four unsaturated monomers: styrene C8H8, benzene C 6H 6, ethylene C2H 4 and acetylene C2H 2. The remote mass spectrometer location restricted species identification to neutral closed-shell molecules in their respective plasmas. Among the peaks in the mass spectra, those directly due to neutrals produced in the plasma were determined following a successful two-step methodology. Firstly, the use of low electron impact energy limited the fragmentation and strongly simplified the cracking patterns. Secondly, attribution of peaks directly due to neutrals was confirmed or ruled out by systematically measuring their appearance potential. In the case of styrene, not less than 48 new molecules were detected. The discussion of the observed stable by-products in each discharge suggested several radicals responsible for their production. Comparing the set of species among the four plasmas showed that the repeated addition of intermediates with one or two carbon atoms and with low H content dominated the chemistry. Under our conditions of intermediate to high W/FM (power over mass flow ratio), the gas-phase plasma polymerization then preferentially occurred through significant fragmentation and recombination. Finally, the measured appearance potentials during plasma provided estimation for the threshold ionization energy of several highly unsaturated hydrocarbons, useful for modeling.

AB - Radio frequency discharges ignited in low-pressure and pure hydrocarbon gases were investigated by mass spectrometry. The plasma process was applied to four unsaturated monomers: styrene C8H8, benzene C 6H 6, ethylene C2H 4 and acetylene C2H 2. The remote mass spectrometer location restricted species identification to neutral closed-shell molecules in their respective plasmas. Among the peaks in the mass spectra, those directly due to neutrals produced in the plasma were determined following a successful two-step methodology. Firstly, the use of low electron impact energy limited the fragmentation and strongly simplified the cracking patterns. Secondly, attribution of peaks directly due to neutrals was confirmed or ruled out by systematically measuring their appearance potential. In the case of styrene, not less than 48 new molecules were detected. The discussion of the observed stable by-products in each discharge suggested several radicals responsible for their production. Comparing the set of species among the four plasmas showed that the repeated addition of intermediates with one or two carbon atoms and with low H content dominated the chemistry. Under our conditions of intermediate to high W/FM (power over mass flow ratio), the gas-phase plasma polymerization then preferentially occurred through significant fragmentation and recombination. Finally, the measured appearance potentials during plasma provided estimation for the threshold ionization energy of several highly unsaturated hydrocarbons, useful for modeling.

KW - acetylene

KW - benzene

KW - ethylene

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