Physics & Astronomy ETDs

Publication Date

Summer 7-14-1969


The problem of photodetachment from homonuclear diatomic mole­cules is treated theoretically, with the aim of providing a calcula­tion of photodetacbment from the molecular oxygen ion. Using a two­-center (spheroidal) coordinate system a one-electron model including direct coulomb, polarization, and approximate exchange interactions is developed, and formulas for scattering and photodetachment cross section are derived. Wave functions representing both bound and free electrons in the field of the neutral molecule are calculated numerically, using adjustable parameters in the exchange and polarization potentials to attain the proper binding energy. The photodetachment cross section is then computed from these wave functions, along with Franck-Condon factors calculated using known vibrational properties of the molecule and the molecular ion. Agreement between calculated and experimental cross sections for oxygen is not satisfactory, the calculated result being a factor of two high. It is shown that uncertainties in various properties of the negative ion can contribute to this discrepancy, but substantial agreement between calculation and experiment can only be achieved be assuming the electron affinity of oxygen to be 0.60 electron volts instead of the widely accepted value of 0.43 eV. This is thought to represent inadequacy in the theoretical model, and suggestions are advanced for possible improvements.

Degree Name


Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Christopher Pratt Leavitt

Second Committee Member

Raymond C. Mjolsness

Third Committee Member

Roy Thomas

Fourth Committee Member

Charles L. Beckel

Document Type


Included in

Physics Commons