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 originale | Anglais |
|---|---|
| Numéro d'article | 045010 |
| Nombre de pages | 14 |
| journal | Plasma Sources Science and Technology |
| Volume | 23 |
| Numéro de publication | 4 |
| Les DOIs | |
| état | Publié - 1 août 2014 |
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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 revue › Article
TY - JOUR
T1 - Plasma polymerization chemistry of unsaturated hydrocarbons: Neutral species identification by mass spectrometry
AU - Gillon, Xavier
AU - Houssiau, L.
PY - 2014/8/1
Y1 - 2014/8/1
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
KW - mass spectrometry
KW - plasma chemistry
KW - plasma polymerization
KW - styrene
UR - http://www.scopus.com/inward/record.url?scp=84905566460&partnerID=8YFLogxK
U2 - 10.1088/0963-0252/23/4/045010
DO - 10.1088/0963-0252/23/4/045010
M3 - Article
AN - SCOPUS:84905566460
VL - 23
JO - Plasma Sources Science and Technology
JF - Plasma Sources Science and Technology
SN - 0963-0252
IS - 4
M1 - 045010
ER -