Neutron-Diffraction Determination of the Crystal Structure and Magnetic Form Factor of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>-Oxygen

Single-crystal neutron-diffraction data have been used to refine the crystal structure of the paramagnetic cubic $\ensuremath{\gamma}$ phase of oxygen at 46 \ifmmode^\circ\else\textdegree\fi{}K. Two of the eight molecules in the $\mathrm{Pm}3n$ unit cell are randomly oriented along the $〈111〉$ axes at the $2(a)$ positions, and the remaining six along the $〈100〉$ axes perpendicular to the fourfold inversion axes at the $6(d)$ positions. Associated with this disorder is a large librational motion with a rms amplitude of about 20\ifmmode^\circ\else\textdegree\fi{}. Magnetic-form-factor values for 27 reflections have been measured by the polarized-neutron technique. Data were collected from large crystals subjected to an applied magnetic field of about 80 kOe in a specially designed split-coil superconducting magnet. The observed values are in good agreement with theoretical calculations described in the following paper based upon the usual molecular-orbital model with two unpaired electrons in the $p\ensuremath{\pi}$ antibonding orbitals.

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