Octaoxygen

Preparation and properties

As the pressure of oxygen at room temperature is increased above 10 GPa, it undergoes a dramatic phase transition to a different allotrope. Its volume decreases significantly,{{cite journal

In this phase, it exhibits a dark-red color, very strong infrared absorption, and a magnetic collapse. It is also stable over a very large pressure domain and has been the subject of numerous X-ray diffraction, spectroscopic and theoretical studies. It has been shown to have a monoclinic C2/m symmetry, and its infrared absorption behaviour was attributed to the association of oxygen molecules into larger units. At 11 GPa, the intra-cluster bond length of the cluster is 0.234 nm, and the inter-cluster distance is 0.266 nm, both longer than the 0.120 nm bond-length in the oxygen molecule .

The formation mechanism of the cluster found in the work is not clear yet, and the researchers think that the charge transfer between oxygen molecules or the magnetic moment of oxygen molecules has a significant role in the formation.

Potential applications

Liquid oxygen is already used as an oxidant in rockets, and it has been speculated that octaoxygen could make an even better oxidant, because of its higher energy density.{{cite news

Researchers think that this structure may greatly influence the structural investigation of elements.

References

References

1. (2006-08-26). "O₈ Cluster Structure of the Epsilon Phase of Solid Oxygen". Physical Review Letters.
2. (2006-09-14). "Observation of an O₈ molecular lattice in the phase of solid oxygen". Nature.
3. Advanced Industrial Science and Technology (AIST). (2006). "Solid Oxygen ε-Phase Crystal Structure Determined Along With The Discovery of a Red Oxygen O₈ Cluster". AZoNano.
4. (2007). "Dark-Red O₈ Molecules in Solid Oxygen: Rhomboid Clusters, Not S₈-Like Rings". [[Angewandte Chemie International Edition]].
5. (2004). "Solid oxygen". Physics Reports.