Time‐resolved Raman spectroscopy of polystyrene under laser driven shock compression. (26th May 2017)

• Record Type: Journal Article
• Authors: Rastogi, Vinay; Chaurasia, S.; Rao, Usha; Sijoy, C. D.; Mishra, V.; Kumar, Manmohan; Chaturvedi, S.; Deo, M. N.
• Is Part Of: Journal of Raman spectroscopy. Volume 48:Number 7(2017)
• Page Start: 1007
• Page End: 1012
• Publication Date: 2017-05-26
• Subjects: polystyrene -- radiation hydrodynamic simulations -- shock compression -- Raman spectroscopy -- shock velocity; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.5166
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : The microscopic and dynamic response of the atactic polystyrene molecules under shock compression at laser power density of 4.9 GW/cm 2 was studied using time‐resolved Raman spectroscopy. The shock pressure estimated in the polystyrene sample was 2 GPa, and the temporal and wavenumber resolutions in these experiments were 3 ns and 3 cm −1, respectively. The shocked polystyrene showed a blue shift of 5 and 7 cm −1 for the 1004 cm −1 (C―C―C ring bending mode ν 12 ) and 1606 cm −1 (C―C ring stretching mode ν 8 a ., respectively. The changes in ν 12 and ν 8 a modes are observed with respect to shock wave propagation. It is observed that the intensities of the Raman peaks decrease and the FWHM of the modes increase due to formation of additional new peaks with delay. The reason behind this indicates the mechanical processes associated with the uniaxial nature of the shock compression. The shock velocity inside the polystyrene was calculated as 2.9±0.12 km/s using the evolution of intensity ratio of peaks with time. This is in good agreement with the shock velocity (3.0 km/s) deduced from the 2D simulations, performed using three temperature radiation hydrodynamic code, THRD. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : Nanosecond time‐resolved Raman spectroscopic experiments with time resolution of 3 ns are performed to study microscopic and dynamical response of aPS under laser‐driven shock compression. The maximum shock pressure in Al and aPS achieved are 5.4 and 2.0 GPa, respectively, at a laser irradiance of 4.9 GW/cm 2 . The pressures in Al and aPS were measured by 2D hydrodynamic simulation and verified by the results obtained from impedance mismatch technique. The calculated shock velocity is 2.9 ± 0.12 km/s.