Collision Studies with Molecular Radicals
- Chief Supervisor
- Assoc. Prof. M.J. Brunger (Flinders University)
- Supervisor
- Prof. P.J.O. Teubner (Flinders University)
- Centre Nodes
- Flinders University
- Australian National University
- Collaborators
- University of California, Davis, Lawrence Berkeley National Laboratories
At the Flinders University node of the Centre a project is available to work on experimental measurements dealing with electron collisions with molecular radicals. Electron collision processes are important across a range of fundamental and applied fields of research. Such collisions in gas discharges and other environments, for example our own atmosphere, often lead to dissociation of molecular constituents and lead to the formation of molecular radicals. The radical products are usually considerably more reactive than their parent molecule due to a combination of effects such as an open shell structure, strong dipole moments or large dipole polarizabilities. As a result, if they are produced in any appreciable amounts in these discharge environments, their subsequent reactions with charged particles, and electrons in particular, can have a significant effect on the overall behaviour of the discharge. This project aims to quantify, for the first time, some fundamental scattering processes between electrons and molecular radicals.
This project uses a state-of-the-art crossed beam apparatus to measure electron collision cross sections for radicals such as CF2 and CF3. These are precisely the species that are of great commercial interest to scientists attempting to model the behaviour of plasma etch reactors for semi-conductor fabrication. Such reactors typically use a fluorocarbon seed gas, and these two radicals are a common by-product.
The apparatus has 3 stages. In the first stage the radical beam is formed using photolysis, the second stage is where the electrons interact with the radical beam of interest, while in the third stage, the radical beam composition is determined using a time-of-flight-mass-spectrometer (TOFMS). Absolute elastic differential cross sections are set using the Relative Flow Technique in the scattering chamber. Theoretical support will be provided by the team at University of California, Davis and Lawrence Berkeley National Laboratories.
Students undertaking this project will develop skills in high vacuum technology, charged particle optics and beams, molecular radical beam production, electron detectors, TOFMS and laser technology. A strong element of the project will also be the development of expertise in molecular and atomic spectroscopy. Other CAMS staff and students involved in this project are Dr Todd Maddern and Mr Leigh Hargreaves.
