Electron attachment lineshapes, cross sections and rate constants at ultra-low energies in several halomethyl and haloethyl molecules

Electron attachment lineshapes, cross sections and rate constants are reported for the molecules CH 2 Br 2 , CF 2 Br 2 , CF 3 Br, CBrCl 3 , BrCN, C 2 H 2 Br 4 , CH 3 I, C 2 H 5 I and 1, 1, 1,-C 2 Cl 3 F 3 . Use is made of the krypton photoionisation method. In addition, the signal intercomparison technique is used to obtain individual channel cross sections and rate constants for Br - and CN - - formation from BrCN, and for Br - and Br 2 - formation from CF 2 Br 2 . Present results in 1,1,1,-C 2 Cl 3 F 3 using a new ion extraction grid geometry are compared with earlier results, and differences discussed in terms of the electric field equipotentials of two extraction systems used in the present work. Approximate potential energy curves for BrCN are presented, and the temperature dependence of the Br - channel cross section discussed.