1. Field F H and Franklin J L 1957Electron impact phenomena and the properties of gaseous ions, (New York: Academic Press) chap. 3.
2. Kline L E and Denes L J 1982Applied atomic collision physics, (eds) H S W Massey, E W McDaniel and B Bederson vol. 3, p. 402
3. Kobayashi T 1978Phys. Lett.
A69 105
4. KrishnaKumar S V and Mitra S K 1986J. Appl. Phys.
60 2177
5. Levin R D and Lias S G. 1982Ionization potential and appearance potential measurements, 1971–1981, NSRDS-NBS71 (Washington, DC: National Bureau of Standards)