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It is shown that electron capture by a reactant may catalyze condensation reactions that otherwise would require higher activation energies in the neutral state. Two competitive processes have been examined in the CO2H2 system: (a) CO 2 +H 2 → HCOOH , (b) CO+H2O→HCOOH, of which only (a) is likely to occur through electron activation. Upon electron capture (threshold around 1 eV), bent hot CO2 reacts with H2 via a stepwise path, leading to formic acid with an overall activation energy close to 2 eV (neutral activation energy 3.17 eV). In the 2 eV energy range, a close contact {HCOO−⋯H•} complex is formed. After electron detachment, a diradical {HCOO• + H•} system results which spontaneously yields HCOOH. The electron is re-emitted with approximately its initial energy so that it can be regarded as a true catalyst for this reaction. |
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