Using a recently constructed high resolution crossed electron/molecular beam apparatus consisting of a hemispherical electron monochromator and a quadrupole mass spectrometer we have measured the relative production cross sections for Cl- and F- via electron attachment to CF2Cl2. The relative Cl- cross section is placed on an absolute scale by reference to an absolute rate coefficient using a calibration method involving in-tegration of the measured anion signal. The most efficient Cl- production process is at about zero energy and its magnitude is resolution limited. The present high resolution value of 6 × 10-16cm2 compares well with an earlier value reported by Chen and Chantry. A second peak is detected at around 0.8 eV in accordance with some of the earlier beam and swarm measurements. The observed production of F- has an appearance energy of 1.9 eV and the energy of maximum cross section is 3.36 eV, the latter value comparing well with several previous studies.
|Number of pages||10|
|Journal||Czechoslovak Journal of Physics|
|Publication status||Published - 1999|