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Title: Shock compression of organic polymers and proteins: Ultrafast structural relaxation dynamics and energy landscapes

Abstract

The response of organic polymers and proteins including poly(methyl methacrylate) and the protein bovine serum albumin (BSA) to a short duration 4.5 GPa shock pulse, termed a nanoshock, is studied using ultrafast coherent Raman spectroscopy (CARS) to monitor density-dependent vibrational frequency shifts of a dye molecule probe. In conventional shock compression experiments, a two-part response of PMMA to fast compression is usually explained with a phenomenological viscoelastic model. The molecular basis for this two-part response is discussed here using an energy landscape model to describe large-amplitude structural relaxation of shocked supercooled liquids. The polymers and the protein show an instantaneous response to the steeply rising shock front, viewed as a vertical transition to a new region of the energy landscape with radically different topography. A slower {approximately}300 ps response is also observed, attributed to large-amplitude structural relaxation along the rugged shocked energy landscape. A viscoelastic model is used to determine an effective shock viscosity {eta} {approx} 3 Pa{center_dot}s for the solid samples. This extremely small value (compared to {eta} > 10{sup 12} Pa{center_dot}s expected for supercooled liquids) is explained as a result of the very large strain rate and the extensive plastic deformation, which causes even seemingly rigid solids tomore » flow. After the short duration ({approximately}2 ns) nanoshock unloads and the samples become frozen, for at least tens of nanoseconds, in a state where the dye vibrational shift indicates a negative pressure of about {minus}1 GPa. The negative pressure means the local density near the dye has decreased, the sample has become more permeable, and the sample is unstable to spontaneous expansion of the polymer chains. The energy landscape model provides a framework for understanding the fast cycle of compression and expansion and how to optimize the generation and detection of large-amplitude structural relaxation processes.« less

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Illinois, Urbana, IL (US)
Sponsoring Org.:
National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); US Department of the Air Force; USDOE
OSTI Identifier:
20050847
DOE Contract Number:  
FG02-91ER45439
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 104; Journal Issue: 17; Other Information: PBD: 4 May 2000; Journal ID: ISSN 1089-5647
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 59 BASIC BIOLOGICAL SCIENCES; POLYMERS; PROTEINS; RELAXATION; DYNAMICS; PMMA; CATTLE; ALBUMINS; SHOCK WAVES; COMPRESSION

Citation Formats

Kim, H., Hambir, S.A., and Dlott, D.D. Shock compression of organic polymers and proteins: Ultrafast structural relaxation dynamics and energy landscapes. United States: N. p., 2000. Web. doi:10.1021/jp994153o.
Kim, H., Hambir, S.A., & Dlott, D.D. Shock compression of organic polymers and proteins: Ultrafast structural relaxation dynamics and energy landscapes. United States. doi:10.1021/jp994153o.
Kim, H., Hambir, S.A., and Dlott, D.D. Thu . "Shock compression of organic polymers and proteins: Ultrafast structural relaxation dynamics and energy landscapes". United States. doi:10.1021/jp994153o.
@article{osti_20050847,
title = {Shock compression of organic polymers and proteins: Ultrafast structural relaxation dynamics and energy landscapes},
author = {Kim, H. and Hambir, S.A. and Dlott, D.D.},
abstractNote = {The response of organic polymers and proteins including poly(methyl methacrylate) and the protein bovine serum albumin (BSA) to a short duration 4.5 GPa shock pulse, termed a nanoshock, is studied using ultrafast coherent Raman spectroscopy (CARS) to monitor density-dependent vibrational frequency shifts of a dye molecule probe. In conventional shock compression experiments, a two-part response of PMMA to fast compression is usually explained with a phenomenological viscoelastic model. The molecular basis for this two-part response is discussed here using an energy landscape model to describe large-amplitude structural relaxation of shocked supercooled liquids. The polymers and the protein show an instantaneous response to the steeply rising shock front, viewed as a vertical transition to a new region of the energy landscape with radically different topography. A slower {approximately}300 ps response is also observed, attributed to large-amplitude structural relaxation along the rugged shocked energy landscape. A viscoelastic model is used to determine an effective shock viscosity {eta} {approx} 3 Pa{center_dot}s for the solid samples. This extremely small value (compared to {eta} > 10{sup 12} Pa{center_dot}s expected for supercooled liquids) is explained as a result of the very large strain rate and the extensive plastic deformation, which causes even seemingly rigid solids to flow. After the short duration ({approximately}2 ns) nanoshock unloads and the samples become frozen, for at least tens of nanoseconds, in a state where the dye vibrational shift indicates a negative pressure of about {minus}1 GPa. The negative pressure means the local density near the dye has decreased, the sample has become more permeable, and the sample is unstable to spontaneous expansion of the polymer chains. The energy landscape model provides a framework for understanding the fast cycle of compression and expansion and how to optimize the generation and detection of large-amplitude structural relaxation processes.},
doi = {10.1021/jp994153o},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
issn = {1089-5647},
number = 17,
volume = 104,
place = {United States},
year = {2000},
month = {5}
}