Shock-induced phase transition of bromoform

Abstract

Optic Radiations for shocked CHBr3 form 37 GPa to 85 GPa were studied by using optic fiber pyrometer. It is found that under shock pressure 45 GPa to about 80 GPa a first-order phase transition happens, which is identified by the recorded radiation signals that has a special “step structure” or two-wave-like structure. A more careful examination of the radiation signals from the shocked CHBr3 indicates that this phase transition is accompanied with a stepped temperature rise resulting from the chemical exothermic reactions in CHBr3 under shock compressions. Another important feature unique to this transition is the measurable relaxation time of the phase transition, which decreases with the increase of shock pressure and vanishes at about 80 GPa.