H. Adaniya

Dissociative electron attachment to carbon dioxide via the 8.2 eV Feshbach resonance

Momentum imaging experiments on dissociative electron attachment (DEA) to CO2 are combined with the results of ab initio calculations to provide a detailed and consistent picture of the dissociation dynamics through the 8.2 eV resonance, which is the major channel for DEA in CO2. The present study resolves several puzzling misconceptions about this system.

A momentum imaging microscope for dissociative electron attachment

We describe an experimental approach to image the three-dimensional (3D) momentum distribution of the negative ions arising from dissociative electron attachment (DEA). The experimental apparatus employs a low energy pulsed electron gun, an effusive gas source and a 4π solid-angle ion momentum imaging spectrometer consisting of a pulsed ion extraction field, an electrostatic lens, and a time- and position-sensitive detector. The time-of-flight and impact position of each negative ion are measured event by event in order to image the full 3D ion momentum sphere. The system performance is tested by measuring the anion momentum distributions from two DEA resonances, namely H(-) from H(2)O(-) ((2)B(1)) and O(-) from O(2)(-) ((2)Π(u)). The results are compared with existing experimental and theoretical data.

Resonant enhanced electron impact dissociation of molecules

In the collision of electrons with molecules and molecular ions, excitation and dissociation are dominated by resonant processes, where the electron becomes temporarily trapped, changing the forces felt by the nuclei. We have carried out calculations on the resonant process leading to dissociative attachment and dissociative recombination. We separate the problem into two steps. First, the resonance parameters are obtained from accurate electron scattering calculations using the Complex Kohn variational method. Then these parameters are used as input to the dynamics calculations. We will illustrate the method with two examples, dissociative attachment in CO2 and dissociative recombination in O+2.

Dissociative electron attachment to water molecule: Experimental study of the dissociation dynamics

The dynamics of the dissociative electron attachment(DEA)to water(H2O, D2O)via three resonances, 2B1, 2A1, 2B2, are investigated using the modified Coltrims spectrometer. The angular dependence of the negative ion shows unique distribution in each resonance indicating the three resonances involve different dissociation dynamics. The energy distribution among the fragments shows considerable amount of three body break.