Studies of low energy electron collisions at sub-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 .…”

“…DA to CH 3 I was studied experimentally by electron beam (Spence and Schulz, 1973) and swarm (Christophorou, 1976;Alge et al, 1984;Shimamori and Nakatani, 1988;Shimamori et al, 1992a;Speck et al, 2000) methods and by the threshold photoelectron attachment technique (Alajajian et al, 1988). In recent LPA studies of DA to the CH 3 I molecule (Hotop et al, 1995;Schramm et al, 1999), performed with meV resolution, a sharp variation of the cross section within a narrow energy interval below the first threshold for vibrational excitation of the symmetric stretch 3 ¼ 1 was observed. This was interpreted in terms of a vibrational Feshbach resonance (Schramm et al, 1999).…”

“…In the LPA study of DA to CCl 4 (Hotop et al, 1995;Klar et al, 2001a; normalization of LPA cross-section to thermal rate coefficient of Orient et al, 1989) the experimental energy resolution was about 0.8 meV, as limited by residual electric fields of about 0.5 V/m (Klar et al, 2001a). Correspondingly, the extrapolation to the VW limit is somewhat less certain than for SF 6 , but model calculations including the residual field and the cross-section (40) yielded very good agreement between the modelled and the measured attachment yield for CCl 4 in the threshold region (Klar et al, 2001a).…”

“…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 !…”

Electron Attachment and Recombination in Dense Molecular Media

“…Electron attachment processes have been extensively studied theoretically and experimentally, and these have been comprehensively summarised in several review papers (Hatano and Shimamori 1981;Hatano 1986Hatano , 1994Shimamori 1991;Chutjian 1992;Sanche 1994;Illenberger 1994;Bardsley 1994;Dunning 1995;Hotop et al . 1995).…”