Determination of absolute partial and total electron impact ionization cross-sections for CF2Cl2 from threshold up to 180 eV: an improved experimental method

Abstract Electron impact ionization of CF 2 Cl 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 2 Cl + 2 , CFCl + 2 , CF 2 Cl + , CCl + 2 , Cl + 2 , CFCl + , FCl + , CF 2 + , CCl + , Cl + , CF + , F + , C + , CFCl 2+ 2 , CF 2 Cl 2+ , CFCl 2+ , CCl 2+ 2 , CCL 2+ and Cl 2+ have been determined. In addition, the total ionization cross-section function of CF 2 Cl 2 is obtained and compared with previous experimental and theoretical results.