Determination of absolute partial and total electron impact ionization cross-sections for CF 2Cl 2 from threshold up to 180 eV: an improved experimental method

Abstract

Electron impact ionization of CF 2Cl 2 has been studied as a function of electron energy from threshold up to 180 eV using a double focussing sector field mass spectrometer (reversed geometry) with an improved ion transmission characteristic. With this set-up complete and/or controlled collection of mass selected parent and fragment ions can be achieved, thus permitting the accurate measurement of quantitative electron impact ionization cross-sections. Absolute partial ionization cross-section functions for the production of CF 2Cl + 2, CFCl + 2, CF 2Cl +, CCl + 2, Cl + 2, CFCl +, FCl +, CF 2 +, CCl +, Cl +, CF +, F +, C +, CFCl 2+ 2, CF 2Cl 2+, CFCl 2+, CCl 2+ 2, CCL 2+ and Cl 2+ have been determined. In addition, the total ionization cross-section function of CF 2Cl 2 is obtained and compared with previous experimental and theoretical results.