Abstract
Single electron attachment to a molecule may invoke quantum coherence in different angular momentum transfer channels. This has been observed in the 14 eV dissociative electron attachment resonance in molecular hydrogen where a coherent superposition of two negative ion resonant states of opposite parity is created, with the s and p partial waves of the electron contributing to the attachment process. Interference between the two partial wave contributions leads to a forward – backward asymmetry in the angular distribution of the product negative ions. Since these two resonant states dissociate to the same n = 2 state of H and H−, this asymmetry is further modified due to interference between the two paths of the dissociating molecular negative ion along different potential energy curves. This interference manifests as a function of the electron energy as well as isotopic composition. This case is akin to the quantum interference observed in photodissociation by one-photon vs two-photon absorption.
Highlights
Dissociative electron attachment (DEA) is a dominant process in any medium in which low energy electrons are present
The momentum image obtained at 4.5 eV along with the angular distribution obtained from the image is shown in figure 1
As the kinetic energy release is low for this resonance, the angular distribution was obtained from the outer edge of the momentum image
Summary
Dissociative electron attachment (DEA) is a dominant process in any medium in which low energy electrons are present. Since electron attachment occurs at distinct energies and leads to distinct molecular fragmentation pathways, DEA provides a way of controlling the chemistry by controlling the creation of reactive species in a medium. This is complementary to the coherent control of chemical reaction using lasers. Electrons being ubiquitous, the possibility of chemical control using electrons may have wider applicability than coherent control of chemical reactions using lasers and is a more practical technology. It is being adopted in plasma technology and nanotechnologies [5]
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