Investigation of the threshold behavior of the cross section for collisional dissociation of diatomic molecules

Author

Scott E. Lasley

Date of Award

3-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Physics

Major Professor

Marianne Breinig

Abstract

The energy spectra of positive ions resulting from the dissociation of singly charged diatomic molecules after collisions with neutral gas targets were measured in coincidence with the neutral fragments. The yields near threshold were studied to determine if they obeyed a two-body threshold law.

N₂⁺, H₂⁺, and ArH⁺ ions were created in an ion source and accelerated to energies between six and twenty keV. The ions collided with He and Xe gas targets and dissociated. Energy spectra of the positively charged fragments ejected in the forward and backward directions were taken with a 160° spherical sector electrostatic analyzer in coincidence with the neutral fragments detected in a charge state analyzer. The spectra were transformed from the laboratory frame to the projectile rest frame. The resulting yields were studied as a function of energy near threshold to determine if their behavior was consistent with the predictions of two-body threshold laws.

The data indicate that two-body threshold laws do describe the energy dependence of the dissociation cross section near threshold. The behavior of the cross section resembles that of the cross section for electron detachment from negative ions measured by other investigators.

Recommended Citation

Lasley, Scott E., "Investigation of the threshold behavior of the cross section for collisional dissociation of diatomic molecules. " Master's Thesis, University of Tennessee, 1988.
https://trace.tennessee.edu/utk_gradthes/13259