Inelastic neutron-scattering measurements were carried out on condensed bulk and confined molecular oxygen. The phase transitions of the oxygen confined in cylindrical pores with diameter of $\approx 94\text{Å}$ are suppressed below their bulk temperatures or in the case of the lowest-temperature transition to the $\alpha$ phase are suppressed entirely. This last observation is possibly due to the low latent heat of transition for this transition. Both elastic and inelastic neutron-scattering data indicate a mixing of oxygen crystal phases upon confinement. Magnetic ordering fluctuations in the $\beta$ phase are found to have similar energy-dependent profiles for confined and bulk excitations showing that the magnetic correlation function decay is unaffected by the finite crystal size in confinement.

• Received 11 September 2008

DOI:https://doi.org/10.1103/PhysRevB.78.214304