Pressure-induced molecular dissociation in iodine at low temperatures

Abstract
Synchrotron x-ray diffraction experiments at low temperatures have revealed that even at 35K the molecular dissociation starts taking place at PS=21.5 and finishes at Pf=26.1GPa. An extrapolation of the phase boundary thus obtained at several temperatures intersects the T=4K line at PS=21.6 and Pf=26.3GPa. This result, inferring the monatomic structure to be realized at P=30GPa and T=4K, leads to a discrepancy against the recent Mössbauer result obtained at the same point in the P-T phase diagram.