Single and double ionization of nitric oxide by electron impact from threshold up to 180 eV

Abstract

Electron impact ionization of nitric oxide was studied as a function of electron energy up to 180 eV. A double focusing mass spectrometer in combination with an improved electron impact ion source (Stephan et al.) was used, alleviating the problems of ion extraction from the source and the transmission of the extracted ions through the mass spectrometer system. Relative partial ionization cross section functions were measured for the processes NO+e→NO++2e and NO+e→NO2++3e. An accurate determination of the cross section ratio q(NO2+/NO)/q(NO+/NO) was made. In addition, absolute partial ionization cross sections for the production of NO+ and NO2+ were determined by normalizing the relative cross sections with two different methods. Using nth root extrapolation an appearance potential of NO2+(X 2Σ+) was determined. The result is compared with previous measurements and theoretical calculations.

New model for electron-impact ionization cross sections of molecules

“…The ''kink'' near Tϭ20 eV is the artifact of the BEB model because the model cannot account for autoionizing states between the lowest B and Tϳ20 eV that must have been included in the experimental cross sections. Indeed, the experimental data by Kim et al 28 ͑not shown in the figure͒ agree very well with those by Rapp and Englander-Golden for Tр40 eV, indicating that the experimental data by Iga et al at 10ϽTϽ30 eV are too low.…”

Absolute partial cross sections for electron-impact ionization of NO and NO2 from threshold to 1000 eV

“…The present NO ϩ cross section is shown in Fig. 5͑a͒ together with those of Kim et al 15 and of Iga, Rao, and Srivastava 2 for which the experimental uncertainties are given as Ϯ20% and Ϯ15%, respectively. The results of Kim et al 15 agree with the present measurements within the combined uncertainties, but above 100 eV the energy dependence of the two measurements differs somewhat.…”

“…5͑a͒ together with those of Kim et al 15 and of Iga, Rao, and Srivastava 2 for which the experimental uncertainties are given as Ϯ20% and Ϯ15%, respectively. The results of Kim et al 15 agree with the present measurements within the combined uncertainties, but above 100 eV the energy dependence of the two measurements differs somewhat. The results of Iga, Rao, and Srivastava 2 lie much higher than the present data and the sharp decrease in the cross section observed by these workers below 40 eV is not in accord with the present measurements, or with those of Kim et al 15 The only previous measurement of the individual N ϩ and O ϩ partial cross sections appears to be that of Iga, Rao, and Srivastava 2 ͓Figs.…”

“…Fiquet-Fayard et al 14 measured the energy dependence of the NO ϩ and NO 2ϩ production cross sections between 250 eV and 2200 eV. Kim et al 15 measured the cross section for the production of NO ϩ and NO 2ϩ ions; while partial and total ionization cross sections were measured by Iga, Rao, and Srivastava. 2 Both of these studies utilized the rare gas crosssection measurements of Rapp and Englander-Golden 13 for normalization of their data.…”

Film growth precursors in a remote SiH4 plasma used for high-rate deposition of hydrogenated amorphous silicon

“…This radical, possibly created at the hot filament from residual N 2 and O 2 , has an ionization potential around 10 eV. 43 The presence of contamination together with a relatively low density in front of the mass spectrometer are probably also the reasons why SiH and Si radicals could not be detected. The low radical densities can be due to a small production rate or to a large loss rate, e.g., by fast reactions with SiH 4 as will be addressed in Sec.…”