Candidate: Sabbir Hossain

Date: Wednesday, August 4, 2004 3:00-5:00 p.m.
2202 Everett Tower

Committee: Dr. John A. Tanis, Chair
Dr. Emanueal Kamber
Dr. Thomas Gorczyca
Dr. Nicolaus Stolterfoht

Abstract: Interference effects associated with the coherent emission of an electron from the identical atomic centers of H2 have been investigated. The interferences are manifested as oscillations in the measured electron yield as a function of the electron energy. This work, conducted at Western Michigan University using the tandem Van de Graaff accelerator, focuses on the ionization of H2 by 1-5 MeV H+ impact. The primary interference phenomenon is analogous to Young-type interferences caused by the passage of light through a pair of closely spaced slits. The observed structures exhibit variations in the oscillation frequency with electron ejection angle and projectile velocity in general agreement with predictions of the Born approximation. Secondary oscillations superimposed in the primary structures and attributed to additional scattering within the molecule have also been observed, but these oscillations have no analogy in Young's experiment. These secondary structures show only slight variations in frequency with changing electron ejection angle and no apparent dependence on the projectile velocity. Additionally, the present results indicate the existence of still higher frequency oscillations, more than ten times those of the primary structures, superimposed on the secondary oscillations. A tentative explanation for these high-frequency oscillations is given in terms of coherent electron emission from the transient molecule formed by the incoming H+ ion and one of the H2 target centers.

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