GRADUATE STUDENT NEEDED for
Non-dipole inner-shell excitation spectroscopy of molecules
GOAL: To use a unique McMaster-built electron scattering spectrometer to study systematically quantitative cross-sections for non-dipole and dipole inner-shell excitation of molecules. This is a relatively unexplored area of molecular spectroscopy in which our group has particular expertise and instrumentation advantages. Spectroscopic surprises are found frequently - see Chem. Phys. Lett. 300 (1999) 676. Recent studies in Quasi-elastic electron scattering have shown surprising results which suggest our measurments may be a simple and direct probe of quantum entanglement. We are also comparing high-momentum trasfer valence electron energy loss spectra to corespondsing inelastc photon scattering and finding significant differences, which may suggest previous assumptions about inelastic electron scattering are invalid.
NATURE of STUDIES: You will carry out systematic studies of the inner-shell excitation spectra of a variety of small molecules with variable scattering angles and impact energies. The overall goal is to develop a sense of the chemical information contained in this data through comparison of molecular series and comparison with high level calculations. Extending quantum codes we currently use for predicting dipole-regime spectra to the non-dipole transitions would be an interesting and appropriate challenge for the right candidate. You will also assist with the maintenance and further development of this complex electron spectrometer. There would also be opportunities to participate in synchrotron radiation experiments to complement the electron scattering results.
SKILLS ACQUIRED: Knowledge of core excitation spectroscopy (NEXAFS, ISEELS); knowledge of all aspects of instrumentation (vacuum, mechanical, electronics, gas handling etc); programming
YOUR THESIS: would report your results, including instrumentation improvements, and their analysis in collaboration with theory. Target molecules are chosen to explore the relationship of inner-shell cross-sections and the electronic and geometric structure. Themes of current interest incude: range of validity of the first Born approxiamtion (an assumtion about strength of interaction as a function of scattering angle); and the relative importance of non-dipole and dipole transitions of the type O 1ssu to pu and O 1ssg to pu in CO2 and other molecules with symmetry-equivalent core excitation sites.
SPECIAL BENEFITS: This project best suits someone with an interest in more fundamnetal aspects of science, or with a strong interest in instrumentation. It would be an excellent preparation for an academic career, as well as any position involving advanced instrumentation and mathematical skills.
© 2010 A.P. Hitchcock / McMaster University.