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.



Research Center/Lab(s)

Center for High Performance Computing Research


This work was supported, in part, by Science Challenge Project under Grant No. TZ2016005, the National Natural Science Foundation of China under Grants No. 11774281 and No. U1532263, Project of Thousand Youth Talents in China, and the US National Science Foundation under Grant No. 1505819.

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)

2469-9926; 2469-9934

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2018 American Physical Society (APS), All rights reserved.

Publication Date

01 Jun 2018

Included in

Physics Commons