Dissociation and dynamics of electron attachment to specific intramolecular structures.

Dissociative electron attachment (DEA) is one of the processes that involve low-energy electrons formed upon high-energy irradiation. Typical DEA studies focus on the detection and yield measurements of negative ions produced as a function of the incident electron energy using mass spectroscopic techniques. Such studies are useful in determining the reaction pathways and the resonant states, which are responsible for molecular decay. However, to provide more knowledge on this process other techniques are necessary to employ. Therefore, in the last two years, we have been developing a new experimental set-up, a velocity map imaging (VMI) spectrometer, which is capable to measure the kinetic energy and angular distributions of the negative ions formed in the DEA process. This type of study provides information about the DEA energy threshold and reveals the symmetry of the resonant states, which are created prior to the dissociation. The construction of the experimental setup has been completed and recently we have made significant progress on the spectrometer calibration, development of analysis codes, and obtained preliminary data for several molecular exemplars. For our preliminary studies, we investigated dissociation dynamics of low-energy electron attachment to simple molecules, containing specific chemical bonds (e.g., peptide bonds) and functional groups (e.g., hydroxyl group). Differential laboratory-frame momentum distribution of fragmented ions has been measured for different incident electron energies over the energy range of resonances, which we measured previously.