Measurement of shock velocity and temperature in laser-shocked carbon disulphide using time-resolved Raman spectroscopy

High-resolution time-resolved Raman spectroscopy of laser-shocked liquid carbon disulfide (CS2) is reported. The symmetric stretching mode (ν1) and first overtone of the bending mode (2 ν2) of CS2 at 656 cm−1 and 802 cm−1 wavenumbers respectively are analyzed to monitor the possible phase transitions occurring in the sample during shock wave propagation in the pressure range 0.4 – 4.4 GPa by varying the laser intensity on target from 0.2 GW/cm2 (40 mJ) to 6.4 GW / cm2 (1300 mJ). A liquid to solid phase transition is observed at 1.5 GPa, as compared to 0.8 GPa in static compression. The difference in these measurements is thought to be due to the high temperatures involved in the dynamic compression experiments described. The shock wave velocities in CS2 at 1.5 GPa and 2.6 GPa are calculated by measuring the intensity ratio of Raman modes emerging from the shocked region to that of the whole sample. 1D radiation-hydrodynamic simulations are performed to corroborate the experimental data. Enhancement of the Raman cross-section of carbon disulfide is observed from 2.5 GPa, which is much lower than the previously reported threshold of 8 GPa as reported by Yoo et al., [24]. This discrepancy in results is thought to be due to the significant contribution of temperature along with the pressure in laser-driven nanosecond single shock experiment.