Electron momentum spectroscopy (EMS) results are presented for the sulfur hexafluoride (SF6) molecule using a high-resolution binary (e, 2e) spectrometer at incident energies (Ei) of 600, 1200, and 2400 eV plus the binding energy. The valence orbital momentum profiles were measured with a binding energy resolution of 0.68 eV and angular resolutions of Δθ = ±0.6⁰, ΔΦ = ±0.85⁰. Whereas the two higher incident energies are in the range where normally EMS measurements do not exhibit an impact-energy dependence, the current experimental data display a dynamic dependence on the impact energies. The measured momentum profiles are compared with predictions from a plane-wave impulse approximation (PWIA) calculation using molecular orbitals obtained from a density-functional-theory quantum-chemistry calculation. The PWIA calculations are in fairly good agreement with experiment only for 2400 eV impact energy, particularly for the summed 1t2u and 5t1u orbitals. We have also compared the experimental results for the 5a1g state with the molecular three-body distorted-wave (M3DW) approach using the orientation-averaged molecular orbital approximation. Unlike the PWIA, the M3DW results are in very good agreement with the experimental data at all three measured incident energies for small momenta, which indicates that dynamical distortion effects are important for this molecule.
X. Wang and S. Xu and C. Ning and O. Al-Hagan and P. Hu and Y. Zhao and Z. Xu and J. Deng and E. Wang and X. Ren and A. Dorn and D. H. Madison, "Dynamic Effects in Electron Momentum Spectroscopy of Sulfur Hexafluoride," Physical Review A, vol. 97, no. 6, American Physical Society (APS), Jun 2018.
The definitive version is available at https://doi.org/10.1103/PhysRevA.97.062704
Keywords and Phrases
Binding energy; Density functional theory; Electron spectroscopy; Energy management systems; Fatigue crack propagation; Molecular orbitals; Molecular orientation; Molecules; Momentum; Spectrometers; Sulfur hexafluoride, Angular resolution; Binary (e ,2e) spectrometer; Distortion effects; Electron momentum spectroscopy; Energy resolutions; High resolution; Quantum chemistry calculations; Valence orbitals, Orbital calculations
International Standard Serial Number (ISSN)
Article - Journal
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01 Jun 2018