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Title: Luminescence from edge fracture in shocked lithium fluoride crystals

Light emitted from a [100] lithium fluoride crystal was characterized under shock wave compression to 28 GPa followed by complete stress release at the edges. We examined the light using time-gated optical spectrometry and imaging, time-resolved optical emission measurements, and hydrodynamic modeling. The shock arrival at the circumference of the crystal was delayed relative to the center so that the two regions could be studied at different times. The majority of the light emission originated when the shock waves released at the circumference of the crystal. Unlike previously reported results for shocked lithium fluoride, we found that the light spectrum is not strictly broad band, but has spectral lines associated with atomic lithium in addition to a broad band background. Also, the emission spectrum depends strongly on the gas surrounding the sample. Based on our observations, the line emission appears to be related to fracture of the lithium fluoride crystal from the shock wave releasing at the edges. Moreover, experimenters frequently utilize lithium fluoride crystals as transparent windows for observing shock compressed samples. Because of the experimental geometries used, the shock wave in such cases often reaches the circumference of the window at nearly the same moment as when itmore » reaches the center of the sample-window interface. Light generated at the circumference could contaminate the measurement at the interface when this light scatters into the observed region. Finally, this background light may be reduced or avoided using experimental geometries which delay the arrival of the shock wave at the edges of the crystal.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3]
  1. National Security Technologies, LLC, Santa Barbara, CA (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. National Security Technologies, LLC, Santa Barbara, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-12-26914
Journal ID: ISSN 0021-8979; JAPIAU
Grant/Contract Number:
AC52-06NA25396; AC52-06NA25946
Type:
Published Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 113; Journal Issue: 13; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1179624
Alternate Identifier(s):
OSTI ID: 1304697