Thermal energy charge transfer reactions of rare-gas ions to methane, ethane, propane, and silane. The importance of franck-condon factors
✍ Scribed by Michael T. Bowers; Daniel D. Elleman
- Publisher
- Elsevier Science
- Year
- 1972
- Tongue
- English
- Weight
- 619 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
Thermal energy charge transfer rate constanis from He+, Ne+. Ar*, Kr+and Xe+ to CH.+, CD4, CaHe, CJHB and SiH4 have been measured using ion cyclotron resonance spectroscopy. The date are interpreted in terms of a model that presumes the magnitude of the rate constant is directly rebated to the magnitude of the Franck-Condon factor connecting the molecule neutral and ion. Additional measurements between N20+, CO;, CO'and N: charge trms ferring to SiH4 indicate the ion-neutral collision distorts, the Franck-Condon manifold from that appropriate to sldden ionization processes (photon or ciectron impact).
Recent experiments [l] on thermal energy charge transfer reactions between rare gas ions and unsaturated halocarbons indicate these processes often occur at impact parameters (ca. 14 A) considerably larger than those predicted from the classical orbiting limit [2] . One possibility suggested by the long range of these reactions is that they may occur via vertical Franck-Condon type processes rather than through long lived intermediates in which the energy is randomized. Franck-Condon processes have been observed for a number of Penning ionization reactioils of He(23S) me&stable atoms with small molecules [3-71. The most deftitive experiments were performed using a combination photoelectron-Penning electron spectrometer 171. In these experiments the neutral mole-* Supported by Grant GP-15628 of the NstionaI Science Foundation and Contract No. 7-100 awarded by the Nation al Aeronautics and Space ,4dminIstration
to the Jet Propui-