Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences


Physics and Astronomy

First Advisor

Dr. Nicholas L. S. Martin


We have measured relative differential cross sections for 350 eV electrons scattered by a helium target in the presence of 1.17 eV photons from an Nd:YAG laser. We report an angular distribution of free-free electrons that were scattered elastically at angles between 15o and 80o and of free-free electrons that underwent the process of electron-impact excitation of helium to its unresolved (1s2s)1S and (1s2p)1P excited states at angles between 1o and 80o. Our experiments test the momentum transfer dependence and the relationship between elastic and inelastic scattering in the Kroll-Watson approximation. We also explored potential light-dressed atom effects for inelastic scattering at low-scattering angles in helium.

We found good agreement between our experimental results and the Kroll-Watson approximation. Due to the presence of an unknown uncertainty in our apparatus, we are unable to unambiguously test the elastic-inelastic relationship of the KWA and our exploration into light-dressed atom effects are inconclusive. Methods to potentially identify and reduce the impact of this unknown uncertainty are discussed for future works.

Digital Object Identifier (DOI)

Funding Information

This work was supported by the United States National Science Foundation under Grants Nos. PHY-1607140 from 2019 to 2021 and PHY-2010102 from 2021 to 2022 (N. L. S. Martin).