In situ Raman spectroscopic studies of polyvinyl toluene under laser-driven shock compression and comparison with hydrostatic experiments Vinay Rastogi, a,b S. Chaurasia, a * Usha Rao, a C. D. Sijoy, c H. K. Poswal, a V. Mishra, c Manmohan Kumar d and M. N. Deo a Shock wave-induced changes in intra-molecular vibrations of polyvinyl toluene (PVT) in a confined geometry target assembly are studied over the pressure range of 0–2.25 GPa. A comparative study of the behavior of PVT in the dynamic and quasi-hydrostatic compression is performed. A 1D radiation hydrodynamic simulation has been performed to calculate the equation of state of the PVT. In present study, the fundamental modes, ν 12 mode at 1001 cm 1 , ν 18a mode at 1031 cm 1 and ν 8a mode at 1602 cm 1 , of PVT are extensively analyzed. At a pressure of 1.58 GPa, peak shift of 4.24, 5.16 and 6.41 cm 1 for the modes 1001, 1031 and 1602 cm 1 , respectively, are observed and are in good agreement with the hydrostatic measurement. Grüneisen parameters are calculated for each modes, which indicates that the primarily volume changes (below 1 GPa) are due to free volume and com- pression of the inter-chain bonds, and not because of changes in intermolecular bond lengths. The shock velocity in the sample at pressure 2.25 GPa is calculated as 3.6 ±0.46 km/s by measuring the ratios of the experimental shocked volume to total volume of the sample measured in the time-resolved measurement and is in good agreement with the simulation result. A comparative study of shock pressure on PVT and polystyrene molecules is also done. These materials are of great interest as they are widely being used as a host material in scintillator detectors, which are used for the measurement of high-frequency electromagnetic radiation. Copyright © 2017 John Wiley & Sons, Ltd. Keywords: polyvinyl toluene; laser-driven shock; confinement geometry; hydrodynamic simulations; Raman peak shift Introduction The insight into the pressure, volume and temperature of the mate- rials under shock compression is important, particularly, in deriving the equation of state (EOS) of the materials and predicting materials response under extreme pressure and temperature conditions. Moreover, if we wish to tailor the behavior of material under shock wave compression, it is essential that we understand the shock wave effect at atomic and molecular level. Vibrational spectroscopy is an effective tool to investigate the real-time effects of shock compression-induced chemical and structural changes in the material. [1–5] Some interesting and sophisticated shock experi- ments are performed during last couples of decades. [5–14] However, the shock-induced changes inside various polymers are still not well understood. Polymers under high pressure have attracted an increase level of interest in recent years, especially under dynamic compression. [7,15–18] Polymer chain have covalent bonds holding the atoms in a chain and much weaker bonds such as hydrogen bonding or Vander Waals bonds, holding the different chains in a solid. Because of their complexity and adoption of different confor- mations, polymeric material exhibits several interesting phenome- non. With the increase in pressure, the semi-crystalline polymers can also go solid–solid phase transition. [19] Various measurements have been performed using a technique such as infrared and Raman spectroscopy to examine the materials behavior at molecu- lar level under static compression. [20–23] More extensive studies of polymers under dynamic compression or high pressure would be very helpful to elucidate the fundamental processes these materials undergo. Plastic scintillator radiation detectors based on polystyrene and polyvinyl toluene (PVT) are well known and are being commercially produced by Saint-Gobain (Pennsylvania state, Malvern, PA, USA) for various radiation monitoring applications. These scintillators are produced by controlled polymerization of the corresponding monomers in the presence of suitable organic fluorescent addi- tives. In our laboratory, plastic scintillators are indigenously being developed for different radiation monitoring applications. Various fluorescent additives and polymerization techniques have been in- vestigated to produce the most efficient scintillator detectors. The technology of development of the detectors is now available for transfer to industry. [24] The light-emitting efficiency of the PVT- * Correspondence to: S. Chaurasia, High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumabi-400085, India. E-mail: shibu@barc.gov.in a High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre (BARC), Mumbai 400085, India b Homi Bhabha National Institute, Mumbai 400094, India c Computational Analysis Division, Bhabha Atomic Research Centre (BARC), Visakhapatnam, India d Radiation and Photo Chemistry Division, Bhabha Atomic Research Centre (BARC), Mumbai 400085, India J. Raman Spectrosc. (2017) Copyright © 2017 John Wiley & Sons, Ltd. Research article Received: 12 May 2017 Revised: 26 June 2017 Accepted: 27 June 2017 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI 10.1002/jrs.5215