This Is AuburnElectronic Theses and Dissertations

Imaging Electron-Driven Dynamics in Dissociative Electron Attachment to Gas Molecules




Moradmand, Ali

Type of Degree





The design and construction of a new ion-momentum spectrometer for the study of electron-molecule interactions at Auburn University (AU) is detailed with emphasis on the phenomenon of dissociative electron attachment (DEA). Applications of the DEA process to varying fields are discussed within the background of molecular theory and the current state of experimental progress. Technical challenges associatied with the construction of a su- personic gas jet, pulsed electron beam, a COLTRIMS-like spectrometer, and list-mode data acquisition are detailed, including demonstrations of the simulation and analytic methods employed. The present apparatus is designed to provide three-dimensional data on angle- resolved fragment momenta resulting from DEA and other electron-molecule interactions. Initial data on the dissociative ionization of methane are shown for calibration. Data on DEA in O2, CO2, and N2O are shown, with comparison to similar measurements and recent theo- retical collaborations with Lawrence Berkeley National Laboratory (LBNL). Improvements over existing experimental data are demonstrated, while surprising results in the angular dis- tributions of anion fragments are observed. Finally, future work with the apparatus including a focus on more complex molecular targets is discussed.