Collision cross-sections resonant energy transfer

Very large rate constants have been found for near resonant energy transfer between infrared active vibrations in CO2 Such near-resonant transitions and their dependence on temperature have also been studied for collisions between vibrationally excited CO2 and other polyatomic molecules as CH4, C2H4, SF et al. The deactivation cross-sections range from 0.28 for CH3F to 4.3 for SFs at room temperature, and decrease with increasing temperature. 

O Reactions.—The cross-section for charge transfer between O- ions and 02(3Sy ) has a maximum value of 7.8 x 10-1 cm2 at an energy of 5 keV of the incident ion,289 whereas that for O- and 02(1A4,) was less than 1 x 10-1 cm2. Reaction rate-constants for reactions of O-, OH-, 02-, Cl-, C03-, and 0H-(H20) with H20 have been measured, and association rate-constants for several ions with COa and S02 tabulated.290 The rate of formation of NO+ by the reaction of 0+ with N2 has been commented upon.291 The formation of H02+ and Os+ by the reaction of 02+( 4 ) with H2 and 02 has been reported,292 and 02+-02, NO+-NO interactions have been considered.293 Rate-constants for reactions of O o4 ,) with N2, Ar, Cl, C02, H2, and 02 have been reported,294 and electron-transfer transitions during the collision of 02, N2, NO, and CO with their respective ions discussed.295 The nearly resonant process (107) has been shown not to occur with high efficiency.29 The lifetime of the 3 state of OH+ has been shown to be 900 ns.87... 

We note that for the molecular case, our results give a good description of the electron capture and electron loss for the collision. For > H2 our results are proportionally lower that those reported by Gealy et al. [36] which were normalized to 6.95 X 10 cm at = 2.0 keV. If we use the same normalization, our results agree well with the experiment. We also note that for the molecular case, the lower the energy of the projectile, the smaller the electron capture cross section, contrary to the atomic case where there is resonant electron transfer. This is a molecular effect, since the closed shell of molecular hydrogen is more stable than the open shell in the atomic case, and thus the electron capture cross section for H2 is not one half that for... 

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