CHARGE-TRANSFER REACTIONS BETWEEN D-10 EV(, O+, AR+, KR+ AND XE+ WITHCH4, C2H6 AND C3H8 AT RELATIVE ENERGIES 1)

Fifteen asymmetric resonant charge transfer reactions, involving the f ive title atomic ions A(+) and the three title molecules B have been s tudied in the relative (center-of-mass) energy range 1-10 eV. Two diff erent tandem mass spectrometers were used to measure limiting cross-se ctions at the highest energies. Time-of-flight and retarding-potential -analysis techniques were used to characterize the contribution from n on-resonant processes, occurring with momentum transfer at low impact parameters. An attempt is made to correlate the magnitudes of the cros s-sections for A(+) + B --> products with molecular parameters of the original reactants: (i) the Franck-Condon factors for B --> B+, and (i i) the cross-section for A(+) + A --> A + A(+). The Franck-Condon fact ors for B --> B+ are shown not to correlate quantitatively, although a propensity rule - low factors legislate low cross-sections - does app ly. The dependence of the cross-section on the nature of A correlates qualitatively with the square root of the symmetric charge transfer cr oss-section for A(+) + A --> A + A(+). The incorporation of all these factors, within the context of Forster theory (which treats the transf er of excitation energy A + A --> A + A*), is considered for charge t ransfer. Qualitative but not quantitative correlations are found, and a formal justification for this is noted. The implications of these re sults for the mechanism of these reactions at thermal energies are bri efly considered.