Magnetic Excitation in Artificially Designed Oxygen Molecule Magnet
  We performed inelastic neutron scattering experiment to study magnetic excitation of O$_2$ molecules adsorbed in microporous compound. The dispersionless excitation with characteristic intensity modulation is observed at $\hbar \omega = 7.8$ meV at low temperature. The neutron cross section is explained by spin dimer model with intradimer distance of 3.1 \AA . Anomalous behaviour in the temperature dependence is discussed in the context of enhanced magnetoelasticity in the soft framework of O$_2$ molecule. 
T. Masuda, S. Takamizawa, K. Hirota, M. Ohba, and S. Kitagawa