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Title: Bright emissive core-shell spherical microparticles for shock compression spectroscopy

Experiments were performed to study the response to shock compression of rhodamine 6G (R6G) dye encapsulated in 1.25 μm diameter silica microspheres. When R6G was encapsulated in microspheres, the emission intensity under steady-state irradiation (the brightness) was 3.4 times greater than the same dye in solution (the free dye). At least part of the brightness improvement was caused by an enhanced radiative rate. When the microspheres were embedded in poly-methylmethacrylate subjected to planar shocks in the 3–8.4 GPa range by laser-driven flyer plates, the dye emission redshifted and lost intensity. The dye emission redshift represents an instantaneous response to changes in the local density. In free dye samples, the shock-induced intensity loss had considerably slower rise times and fall times than the redshift. When dye was encapsulated in microspheres, the time dependence of the intensity loss matched the redshift almost exactly over a range of shock pressures and durations. The faster response to shock of dye in silica microspheres was explained by dye photophysics. The microsphere environment decreased the singlet state lifetime, which decreased the rise time, and it also decreased the triplet state lifetime, which decreased the fall time. Since it is much easier and more convenient to make measurements ofmore » intensity rather than spectral shift, these microspheres represent a substantial improvement in optical sensors to monitor shock compression of microstructured materials.« less
Authors:
; ;  [1]
  1. School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
Publication Date:
OSTI Identifier:
22308465
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BRIGHTNESS; COMPRESSION; DYES; EMISSION; IRRADIATION; LASER RADIATION; LIFETIME; LOSSES; MICROSPHERES; MICROSTRUCTURE; PRESSURE RANGE GIGA PA; PULSE RISE TIME; RED SHIFT; SENSORS; SILICA; SPECTRAL SHIFT; SPECTROSCOPY; SPHERICAL CONFIGURATION; STEADY-STATE CONDITIONS; TIME DEPENDENCE