Electron Attachment to Molecules in Very High Pressure Gases
In this thesis, electron capture mechanisms and reaction schemes have been developed for electron attachment to 02 , c6H6 , and c2H5Br embedded in high densities of N2 (P N2 s 36 atm), Ar (PArs 56 atm) , c2H4 (PC H s 22 atm) , and C2H6 (PC H s 23 atm). As the density of each 2 4 2 6 medium increases, each is found to affect the attachment rate in a different manner, indicating the profound effect and importance of the environment on the electron attachment process. The results of a study on the capture of slow ( < 1 eV) electrons by o2 in high pressures of N2 , c2H4, and c2H6 media are presented and discussed and a model is presented to account for the experimental observations in each case. Benzene has also been found to capture slow electrons in high pressures of N2 and Ar media and a model is presented to account for the observed results. The finding that c6 H6 captures electrons in the gas phase forces the conclusion that (EA) B > 0 eV in contrast to the accepted view that (EA)B < 0 eV. Bromoethane has been found to capture slow (< 3 eV) electrons in high pressures of N2 and Ar and a reaction mechanism is presented which accounts for the relative magnitudes of the rate constants for autoionization, dissociation, and collisional stabilization. The high pressure data for electron attachment to o2, c6 H6, and c2H5 Br to form the respective negative ions have been extrapolated to liquid densities to yield values of the attachment rate in the liquid state. These values generally are in reasonable agreement with those obtained by other investigators using liquid solutions. ill