Compressional, temporal, and compositional behavior of H2-O2 compound formed by high pressure x-ray irradiation.

X-ray irradiation was found to convert H(2)O at pressures above 2 GPa into a novel molecular H(2)-O(2) compound. We used optical Raman spectroscopy to explore the behavior of x-ray irradiated H(2)O samples as a function of pressure, time, and composition. The compound was found to be stable over a period of two years, as long as high pressure conditions (>2 GPa) were maintained. The Raman shifts for the H(2) and O(2) vibrons behaved differently from pure H(2) and O(2) as pressure was increased on the compound up to 70 GPa, indicating that it remains a distinct, molecular compound. Based on spectra taken from different locations in a single sample, it appears that multiple forms of the H(2)-O(2) compound exist. The structure and composition of the starting material plays an important role in compound formation, as we found that hydrogen-filled ice clathrate C(2) (H(2))H(2)O did not undergo the same dissociation as observed in ice VII upon x-ray irradiation until pressure was increased to above 10 GPa.