Abstract
Pressure dependence of the orthorhombic polymeric phase of C60 has been studied by angle-dispersive, X-ray powder diffraction in a diamond anvil cell. Transformation to a new phase through the simultaneous action of pressure and X-rays was observed between 0.2 and 1.66 GPa. A possible structure of this new phase of C60 is discussed. Further increase in pressure leads gradually to the irreversible formation of a disordered phase.