Brief Review of Electron Collision Studies of Molecules Relevant to Plasma

Abstract

A brief review of the electron collision studies of perfluorocarbons and SF 6 relevant to plasma is presented. The use of these gases in various applications of plasma is highlighted, and their possible replacement with gases that have a low global warming potential is suggested. The results for a few simple fluorocarbons are presented, i.e., C 2 F 2 , C 3 F 4 , and C 4 F 6 for elastic scattering and C 2 F 6 for ionization, and the requirement for further investigation is highlighted. This review is not extensive; however, it presents an important step towards understanding the lack of cross-section data for numerous fluorocarbon molecules/radical species. In addition, it highlights the requirement for the detailed study of fluoroketones and fluoronitriles, which are possible substitutes for SF 6 for various electron collisional processes other than ionization.

Low-Energy Electron Scattering from c-C4F8

“…We could also confirm the presence of shape resonance at around 3~4 eV and Feshbach resonance at 7.73 eV, in accordance with the earlier calculation and the experimental dissociative attachment study to c-C 4 F 8 . The present study suggests that we could use similar models and approximations to study more complex targets, such as c-C 5 F 8 , c-C 6 F 8 , C 7 F 8 , C 7 F 14 , and c-C 10 F 8 , and test their validity for replacing the PFC gases with higher globalwarming-potential ones, as highlighted in a recent review article [13]. It is quite clear that there is lack of studies for larger fluorocarbons, and even for a smaller targets, scarcity of data is seen, and hence, we hope this study can motivate others to investigate more on this subject.…”

“…Recently, we investigated electron collision studies with C 2 F 2 [10], C 3 F 4 [11], and C 4 F 6 [12] isomers, for which there were very little data in the literature, highlighting the importance of the need for more investigation. The importance of investigating fluorocarbons and other feedstock gases for replacing currently used higher global-warming-potential gases has been highlighted in a recent review [13]. For c-C 4 F 8 , experimental data of total and ionization cross-sections are available, but clearly, there is a lack of detailed theoretical investigation for this important target.…”

Electron and Positron Impact Ionization of SF6−nHn(n = 0 − 6); {SCln, SFn−1Cl(n = 1 − 6)} and SF5X(X = CN, CFO)

“…Numerous scattering studies have been conducted on several perfluorocarbons (PFCs), perfluoroketons (PFKs), and perfluoronitriles (PFNs) that could be potential alternatives to or replacements for SF 6 [7][8][9]. A recent review article also highlighted the possible replacement gases for SF 6 [10]. Any substitute for the SF 6 must posses a low GWP, high dielectric strength, good thermal stability, and lower ozone-depleting potential (ODP) [11,12], and should also have a lower electron attachment cross-sections [13].…”