Absolute electron impact ionization cross-sections and polarisability volumes for C2 to C4 aldehydes, C4 and C6 symmetric ethers and C3 to C6 ketones

Absolute total electron impact ionization cross-sections from 15 to 285 eV are reported for the C-2 to C-4 aldehydes, the C-2, symmetric C-4 and C-6 ethers and C-3 to C-6 ketones. The reproducibility of the measured cross-sections over the full energy range is better than +/- 4%, and absolute cross-sections measured for N-2 and SF6 as reference species are in excellent agreement with values reported by several other groups claiming accuracies of around +/- 5%. Monotonic relationships previously shown to exist between maximum ionization cross-section and polarisability volume and between maximum ionization cross-section and the total number of carbon atoms in the skeletal chain are shown to apply to the aldehydes, ethers and ketones reported here. These relationships provide useful means for estimating unknown cross-sections with available literature polarisability volumes in good accord with values estimated from the measured maximum ionization cross-sections. The experimental data were also compared with calculations carried out using the binary encounter Bethe (BEB) method for the calculation of total ionization cross-sections. (C) 2008 Elsevier B.V. All rights reserved.