Ion Chemistry in Cold Plasmas of H2 with CH4 and N2

Tanarro, Isabel; Herrero, Vı́ctor J.; Islyaikin, Andrey M.; Méndez, Isabel; Tabarés, F.L.; Tafalla, D.

doi:10.1021/jp073569w

Cited by 26 publications

(41 citation statements)

References 69 publications

(187 reference statements)

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“…A(m/z) = k QMS · σ + (mol) · N(mol) · I F (z) · F F (m) · S (m/z), (A.1) where A(m/z) is the integrated area below the QMS signal of a given mass fragment m/z during photon-induced desorption, k QMS is the proportionality constant, σ + (mol) the ionization cross section for the first ionization of the species of interest and the incident electron energy of the mass spectrometer, N(mol) the total number of desorbed molecules in column density units, I F (z) the ionization factor, that is, the fraction of ionized molecules with charge z, F F (m) the fragmentation factor, that is, the fraction of molecules of the isotopolog of interest leading to a fragment of mass m in the mass spectrometer, and S (m/z) the sensitivity of the QMS to the mass fragment (m/z) (see Tanarro et al 2007, and references therein).…”

Section: Appendix A: Calibration Of Qmsmentioning

confidence: 99%

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes

Martín-Doménech

Manzano-Santamaría

Muñoz

et al. 2015

A&A

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Context. Ice mantles that formed on top of dust grains are photoprocessed by the secondary ultraviolet (UV) field in cold and dense molecular clouds. UV photons induce photochemistry and desorption of ice molecules. Experimental simulations dedicated to ice analogs under astrophysically relevant conditions are needed to understand these processes. Aims. We present UV-irradiation experiments of a pure CO 2 ice analog. Calibration of the quadrupole mass spectrometer allowed us to quantify the photodesorption of molecules to the gas phase. This information was added to the data provided by the Fourier transform infrared spectrometer on the solid phase to obtain a complete quantitative study of the UV photoprocessing of an ice analog. Methods. Experimental simulations were performed in an ultra-high vacuum chamber. Ice samples were deposited onto an infrared transparent window at 8K and were subsequently irradiated with a microwave-discharged hydrogen flow lamp. After irradiation, ice samples were warmed up until complete sublimation was attained. Results. Photolysis of CO 2 molecules initiates a network of photon-induced chemical reactions leading to the formation of CO, CO 3 , O 2 , and O 3 . During irradiation, photon-induced desorption of CO and, to a lesser extent, O 2 and CO 2 took place through a process called indirect desorption induced by electronic transitions, with maximum photodesorption yields (Y pd ) of ∼1.2 × 10 −2 molecules incident photon −1 , ∼9.3 × 10 −4 molecules incident photon −1 , and ∼1.1 × 10 −4 molecules incident photon −1 , respectively. Conclusions. Calibration of mass spectrometers allows a direct quantification of photodesorption yields instead of the indirect values that were obtained from infrared spectra in most previous works. Supplementary information provided by infrared spectroscopy leads to a complete quantification, and therefore a better understanding, of the processes taking place in UV-irradiated ice mantles.

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Section: Appendix A: Calibration Of Qmsmentioning

confidence: 99%

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes

Martín-Doménech

Manzano-Santamaría

Muñoz

et al. 2015

A&A

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“…Films of hard a-C:H characteristics were produced on stainless steel (SS) and silicon samples by PACVD in DC glow discharge reactors, similar to those described in [2,8]. The geometry of the chamber was cylindrical (Ø250 mm, 300 mm height) with a rod-like anode entering from a side of the reactor.…”

Section: Film Deposition and Simulation Of Gap Structuresmentioning

confidence: 99%

Removal of carbon films by oxidation in narrow gaps: Thermo-oxidation and plasma-assisted studies

Tanarro

Ferreira

Herrero

et al. 2009

Journal of Nuclear Materials

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a b s t r a c tThe removal of hard amorphous hydrogenated carbon (a-C:H) films from narrow gaps simulating the macro-brush structures present in controlled fusion devices has been investigated. Films with a thickness of 50-150 nm were generated through plasma-assisted chemical vapor deposition (PACVD) in glow discharges of CH 4 /He on Si and stainless steel plates. The deposited plates were then arranged to form sandwich structures building narrow gaps and were subjected to erosion by exposure to O 2 /He plasmas and to thermal oxidation by O 2 and by a NO 2 /N 2 (1:1) mixture. In the plasma etching experiments, the deposited layers were only partially removed by the plasma at the side wall gap surfaces, but were efficiently removed at the bottom of the gap. In the thermo-oxidation experiments, the deposited films were effectively and homogeneously removed with oxygen at 670 K and with the NO 2 /N 2 mixture at T > 570 K.

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“…In the literature different diagnostics were applied to study the interaction between nitrogen and hydrogen containing mixtures. In fact, one can find a lot of information for totally different experimental conditions: catalyser based HCN production at atmospheric pressure [3] , production of synthetic materials and gas phase reactions in microwave plasmas [4,5], low temperature plasma studies [6,7,12,13] as well as experiments in fusion experiments [8]. The spectrum of intermediate species and final products covers nearly all possibilities for C x H y N z (for x = 1,2,.. y =1…6 , z =1,2).…”

Section: Introductionmentioning

confidence: 99%

The scavenger effect – Does it work?

Bohmeyer

Tabarés²,

Baudach

et al. 2009

Journal of Nuclear Materials

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The influence of nitrogen injection on the formation of a-C:H films in areas far away from the plasma as well as close to the plasma boundary was studied in the PSI-2 device for collector temperatures between 310 and 350 K. The balance between deposition and erosion determines the net growth rate. Small amounts of nitrogen (Φ(N 2 ) ≈ Φ(CH 4 ) ≈ 2% Φ(H 2 )) strongly reduce the net growth rate in H 2 /CH 4 mixtures. While N 2 injection does not influence erosion far away from the plasma it increases erosion close to the plasma boundary. The experiments show clear evidence for a scavenger effect due to the injected nitrogen. The conversion from N 2 to active species takes place in the hot plasma region.

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Ion Chemistry in Cold Plasmas of H₂ with CH₄ and N₂

Cited by 26 publications

References 69 publications

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes

Removal of carbon films by oxidation in narrow gaps: Thermo-oxidation and plasma-assisted studies

The scavenger effect – Does it work?

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Ion Chemistry in Cold Plasmas of H2 with CH4 and N2

Cited by 26 publications

References 69 publications

UV photoprocessing of CO2ice: a complete quantification of photochemistry and photon-induced desorption processes

UV photoprocessing of CO2ice: a complete quantification of photochemistry and photon-induced desorption processes

Removal of carbon films by oxidation in narrow gaps: Thermo-oxidation and plasma-assisted studies

The scavenger effect – Does it work?

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Ion Chemistry in Cold Plasmas of H₂ with CH₄ and N₂

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes

UV photoprocessing of CO₂ice: a complete quantification of photochemistry and photon-induced desorption processes