Raman spectroscopy of poly (methyl methacrylate) under laser shock and static compression

Time-resolved Raman spectroscopy for visualizing molecular fingerprint snapshots at nanosecond time scale is a useful tool for detailed understanding of in situ shock behaviour of materials. This technique was applied to study the changes in molecular vibrations of poly (methyl methacrylate) (PMMA) under laser driven shock compression up to similar to 1.9 GPa in a confinement geometry. A layered target configuration is used to enhance the shock pressure. The vibrational modes are measured as a function of dynamic shock and static compression. The Gruneisen parameters and bond anharmonicities in PMMA are determined using compression behaviour of Raman modes. The deduced shock velocity (similar to 3.5 +/- 0.4 km/s) in PMMA based on the time evolution of shocked Raman mode at 1.9 GPa is in agreement with the one calculated (similar to 3.7 km/s) from 1-D radiation hydrodynamic simulations. A comparative study on shock experiment and static high pressure Raman spectroscopic measurements is done. Static pressure measurement up to similar to 16 GPa show rapid blue shifting of C-H stretching modes.