Shock Temperature of NaCl Measured with Wide‐Band Optical Radiometry

Shock temperature of NaCl was measured with time‐resolved (3‐nanosecond resolution) wide‐band optical radiometry observing the radiation ranging from 0.6 to 13 μm in the pressure range between 17 and 43 GPa. In case of samples above 2000 K, the emitted radiation was measured with a visible to near‐IR radiometer (0.6–1.6 μm). This radiation associated with a phase transition which arises at the defect sites such as dislocations. An IR radiometer sensitive to 9–13 μm was used to measure the bulk temperature below 1000 K. In the mixed‐phase region between 23 and 33 GPa, thermal heterogeneity was observed in shock‐loaded NaCl. In the low‐pressure phase (B1) between 17 and 21 GPa, the shock temperature obtained with IR radiometer was almost 400 K lower than the values obtained by Fritz et al.