Total and double differential cross sections of ion-pair formation in collisions of K atoms with SnCl4 and CCl4

Abstract

Dissociative ion-pair formation in collisions of fast potassium atoms with benzene and fluorobenzeneThe reaction K + ACl,----K+ + (A -Cl.r· with A = Sn and C was examined as a function of the collision energy from threshold up to about 40 eV in the c.m. system. Total cross sections of the mass-selected negative ions and doubly differential cross sections (energy and angle) of the K+ ions have been determined. Electron affinities, bond energies, and electronic excitation were calculated from the appearance potentials. In addition, the total cross sections for SnCI. were measured and are contrasted with the earlier results of CCI, from Dispert and Lacmann. Although both parent molecules have the same electron affinity within their error limits (2.2 eV for SnCI. and 2.0 eV for CCI.) and the same dissociation energy for the negative ions of 1.4±0.2 eV, the product ion yields differ drastically. The main negative ion yield in K + SnCI. results from SnCl.formation (over 80%). Its lowest dissociation channel leads to SnCI; formation, while Cl-ions are the main ions produced (90%) from CCl" with only 7% leading to CCl; + CI formation at higher energies. These results support orbital energy considerations of electron addition to SnCl, and CCI. as applied to the results of reactive colJisions of these molecules. The electron affinity and an electronically excited state of SnCl 3 have been also determined. Morse potentials of CCI. and SnCl. were fitted to the experimental results of energy loss measurements from this work. The vertical electron affinities thus derived are 1.15 eV for SnCI. and -1.0 eV for CCl •.

The negative ion chemistry of nitric oxide in the gas phase

“…Carbon tetrachloride (EA ¼ 2.0 AE 0.2 eV) (Lacmann et al, 1983) and methyl iodide (EA ¼ 0.2 AE 0.2 eV) (Rinden, Maricq, & Grabowski, 1989) undergo similar reactions with NO À despite the large difference in electron affinities (Moutinho, Aten, & Los, 1974;Dispert & Lacmann, 1978;Chupka et al, 1985). Both substrates give rapid formation of the halide anion as the exclusive reaction channel, either by dissociative electron transfer or displacement (Eqs.…”

Combined Experimental and Theoretical Studies on Electron Transfer in Potassium Collisions with CCl4

“…Finally, in collisions of neutral potassium atoms (K) with tetrachloromethane yielding ion-pair formation, Lacmann and co-workers reported K + energy loss measurements in the forward direction with a local maximum at approximately 0.9 eV and assigned them to a transition to the purely repulsive 2 T 2 state.…”

The structure of the CC1n− (n = 1–4) anions and electronic affinities of the corresponding neutrals

“…The CC14-anions formed according to reaction [2] will fragment due to the excess energy transferred from the potassium atoms during the collision. Lacmann et al (6) were able to deduce a rough estimate of the energies for the different dissociation channels based on the energy loss spectrum. The estimates, which likely are rough upper bounds, are compared to calculated dissociation energies in Table 6.…”

“…Lacmann et al (6) have carried out collision experiments with CC14 and a beam of potassium atoms. The CC14-anions formed according to reaction [2] will fragment due to the excess energy transferred from the potassium atoms during the collision.…”

“…The anions are, on the hand, scarce. CC14 molecule is one of the most extensively studied species of The CCl4-was for the first time as as this kind along with other halogen substituted methanes (1)(2)(3)(4)(5)(6)(7)(8) 1953 (26)(27)(28) and the adiabatic electron affinity (EA,,) of the and SF6. Much of the experimental data on electron attachment Parent CC14 molecule was first determined by magnetron techniis obtained from collision experiments with a beam of electrons ques (29)(30)(31) to be equal to2.06eV.…”