Dissociative electron attachment to CCl4 molecules at low electron energies with meV resolution

Resonance and Threshold Phenomena in Low-Energy Electron Collisions with Molecules and Clusters

“…0) which -in terms of Eq. (40) (Klar et al, 1992b) and ¼ 0.59(6) for CCl 4 (Hotop et al, 1995;Klar et al, 2001a), in both cases distinctly larger than the prediction obtained from the Klots formula (21), namely K ¼ 0.228 for SF 6 and K ¼ 0.299 for CCl 4 . For SF 6 , Schramm et al (1998) measured the attachment yield at residual electric fields as low as 0.01 V/m and negligible laser bandwidth for electron energies from 10 meV down to 20 meV; they confirmed the results of Klar et al (1992b) for the parameter .…”

“…32 we compare the recommended experimental DA cross-section for CCl 4 (consisting of the LPA cross-section at energies below 173 meV and electron beam data due to Chu and Burrow (1990) at higher energies, see also Klar et al, 2001a) with the VW s-wave prediction and the LPA fit of Klar et al (2001a). The slope of the experimental curve is steeper than that given by the VW model.…”

“…The yield is proportional to the absolute cross-section e (E) ¼ NY e (E) for anion formation due to free electron attachment. The normalization constant N is conveniently determined with reference to known thermal energy attachment rate coefficients k e (T) (Smith and Sˇpanel, 1994;Christophorou, 1996) using the expression (Chutjian and Alajajian, 1985;Klar et al, 1992bKlar et al, , 2001aChutjian et al, 1996;Schramm et al, 1999Schramm et al, , 2002 …”

“…33a we present the energy-dependent rate coefficient k e (E) for free electron attachment to CCl 4 over the range (0.8-173) meV (Hotop et al, 1995;Klar et al, 2001a). The limiting LPA value 12.3(19) Â 10 À7 cm 3 s À1 (full circle, Klar et al, 2001a) is in good agreement with the most recent rate coefficient k nl % 11(2) Â 10 À7 cm 3 s À1 (open circle, Dunning, 1995;Frey et al, 1995) for RET in K ** (np) þ CCl 4 collisions at high principal quantum numbers (n ! 70); they are both distinctly higher than the VW capture rate coefficient k c (E !…”

“…32, Klar et al (2001a) calculated thermal DA rate coefficients k e (T e ) for fixed gas temperature T G ¼ 300 K as a function of electron temperature T e . In Fig.…”