Threshold ionization mass spectrometry of reactive species in remote Ar∕C2H2 expanding thermal plasma

Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Triple stage threshold ionization mass spectrometry is successfully implemented in an Ar/ C 2 H 2 expanding thermal plasma setup. More than 20 hydrocarbon radicals and molecules formed in the plasma, including for example the C 2 H, C 3 , C 3 H, and C 3 H 2 radicals or C 3 H 4 or C 4 H 2 molecules, are measured and their absolute densities are determined. Thanks to a careful design, a high sensitivity of the instrument is achieved and species with densities as low as 1 ϫ 10 16 m −3 can be detected. Issues related to the absolute density calibration procedure are considered. The proper determination of the background signal by means of a beam chopper and the influence of the chopper on the measurement are discussed and the possible composition distortion of the sampled beam due to the collisions in the sampling orifice is checked. Furthermore, reported values of electron impact ionization cross sections of hydrocarbon species are compared and, based on their similarity in the near threshold energy region, the C 2 H 2 electron impact ionization cross section is proposed as a reasonable approximation for other hydrocarbon radicals. The results for C, CH, and C 2 radicals are compared with previous cavity ringdown absorption spectroscopy measurements and a good agreement is obtained.

Multiplasmon excitations in electron spectra of small systems irradiated by swift charged projectiles

“…The C 3 has 12 valence electrons which group into 5 (degenerated) states with a large gap of about 7 eV between the two deepest levels and the three higher ones. Our calculated value of the IP for C 3 , E IP = −ε 5 = 10.8 eV, is in fair agreement with other calculations (12.0 eV [44,45]) and experimental measurements (11.6 eV [46], 12.1 eV [47], and 13.0 eV [48]). Our calculated IP is a bit too low.…”

Ionization Thresholds of Small Carbon Clusters: Tunable VUV Experiments and Theory

“…Except for this, there are no previous data for photoionization thresholds of these small carbon clusters. However, this data can be compared to ionization potentials determined previously by Eyler and coworkers using charge transfer bracketing experiments, 31 and to more limited data from electron impact ionization by Benedikt et al 100 The IP values determined from these previous experiments are also given in Table 1 within overlapping error bars. The electron impact (EI) ionization experiments also determined thresholds that are higher than ours.…”

“…It 25 therefore seems that the CTB experiment was problematic for this cluster. An additional experimental value for this IP has been reported by Benedikt et al 100 using electron impact ionization of species produced in an acetylene plasma. Their value of 11.9 ± 0.5 eV is higher than our TPI value, but more in line with our theoretical predictions.…”

Unraveling the deposition mechanism in a-C:H thin-film growth: A molecular-dynamics study for the reaction behavior of C3 and C3H radicals with a-C:H surfaces

“…5,9 It was established that the major growth species depend on the ratio ͑F͒ between the C 2 H 2 load and the Ar + and electron fluence emanating from the arc. At high C 2 H 2 flows ͑F Ͼ 1͒, it was established that C 3 and C 3 H are the major growth species, using threshold ionization mass spectrometry 10 ͑TIMS͒. Deposition then occurs at a high rate, up to 70 nm/ s, and films with a considerable hardness ͑14 GPa͒, refractive index ͑2.2͒, and low roughness ͑3.7 nm͒ are obtained.…”