The program of the experimental low energy electron collisions group at California State University Fullerton is currently focused on the study of electron collisions with inert rare gases (neon, argon, krypton and xenon) and molecular hydrogen (also a closed shell molecule). The dynamics of electron impact ionization of the rare gas target (specifically neon and xenon) revealed some very interesting results last year. These showed for neon that in the near-threshold ionization region in specific scattering cases (forward scattering and where the energy of either of the two outgoing electrons was very low), the process seems to be inhibited by the electron being sucked into the polarized ion-core. The group has proposed an interesting hypothesis for this effect. Presently it is delving deeper into such mechanisms, with similar experiments with argon and krypton, A second series of experiments in the future hopes to provide detailed information regarding the imparting of angular momentum by the scattering electron to the rare gas target or molecular hydrogen in coincidence with the scattered electron, especially to test state-of-art theories for large angle scattering near backward scattering angles.
The experimental low energy electron collisions group at California State University Fullerton is a very active group, where almost half of the physics department's majors participate in research. The group also has a strong publication record with undergraduate student authors on papers in top peer-reviewed journals. The program generates by far more PhD-bound students than any other program in the department. Broader impacts also involve education of a significant number of high school students as well as under-represented women and minority students (California State Fullerton is a nationally recognized Hispanic serving college).
We have managed to upgrade this system (following a major disaster when the harness holding the spectrometer the fall caused the breakage of a bunch of things including parts of the spectrometer and the VUV polarization detector) to take data at higher scattering angles. The observation of coherence and correlation parameters at large scattering anges at low incident energies has not been done yet for most of the rare gases. Our system can tackle this and we are presently taking data on Ne which will be followed by Xe. In our funding cycle, we published two papers on small angle coherence and correlation parameters: (1) for Ne at 25eV to look at unusual angular momentum transfer in electron-impact excitation of neon, by L. R. Hargreaves, C. Campbell, and M. A. Khakoo, in collaboration with Oleg Zatsarinny and Klaus Bartschat of Drake University, and extended our measurements to 30eV including Ar and, (2) for polarization correlations for electron-impact excitation of the resonant transitionsof Ne and Ar at low incident energies with L. R. Hargreaves, C. Campbell, and M. A. Khakooin collaboration with J. W. McConkey at the University of Windsor, Canada Oleg. Zatsarinny and K. Bartschat and A. D. Stauffer and R. P. McEachran at York University, Canada. The results pointed out an opposite and therefore unsusal direction of angular momentum transfer perpendicular to the scattering plane, in contrast to classical grazing incidence models of small angle scattering. Presently we do not have a semi-classical explanation of our observations. The results in Ar were a significant improvement in earlier measurements in Ar and helped to brdge the disagreement between theory and experiment. In all this we worked earlier with three undergraduate students Colin Campbell (now doing PhD at ANU, Australia), Brandon Grisanti (went to U. Nevada, Reno to do PhD), Ken Varella (doing PhD at Penn. State). Presently we have Robert Wright who is involved in this project and doing his Masters degree. Also we had a postdoctoral fellow (Leigh Hargreaves) who came from Flinders University in Australia. Leigh is now a faculty member in our department. As aforementioned, we have significantly improved the syatem which is now running very well and taking further data in Ne but at large scattering angles.
