Abstract
Powder x-ray diffraction and infrared absorption experiments of solid oxygen at room temperature have been carried out up to 151 GPa and 60 GPa, respectively. The structural transition from the ε to ζ phase observed at 96 GPa in our previous experiment was reproduced. Stability of the ζ phase was confirmed up to 151 GPa. In infrared absorption experiments with a single-crystal of the ε phase, the IR-active vibron fundamental around 1500 cm-1 split into at least three bands. The pressure dependence of frequence of the IR vibron fundamentals had a minimum at 20 GPa and above 30 GPa showed positive pressure coefficients between 1. 2-1. 7 cm-1/GPa.
