TY - GEN
T1 - Shock compression spectroscopy of quantum dots
AU - Christensen, James M.
AU - Banishev, Alexandr
AU - Dlott, Dana D.
N1 - Funding Information:
The research described in this study was based on work supported by the US Air Force Office of Scientific Research under award FA9550-16-1-0042 and the Defense Threat Reduction Agency under award HDTRA1-12-1-0011. James M. Christensen acknowledges support from a National Defense Science and Engineering Graduate Fellowship.
Publisher Copyright:
© 2018 Author(s).
PY - 2018/7/3
Y1 - 2018/7/3
N2 - We have investigated CdSe quantum dots (QDs) as photoluminescent probes of shocked solids. They could be especially useful for composite materials, where the individual components could be tagged with different color QDs. The QDs are tiny (4 nm) spherical emitters, pumped by a continuous laser during shock or diamond anvil experiments up to 12 GPa. In the diamond anvil the QDs are hydrostatically compressed and the emission blueshifts with increasing pressure. By contrast, in shock experiments the QDs are embedded in a hard glass or a soft polymer matrix and subjected to uniaxial compression, which should mechanically deform them, and the emission redshifts with increasing pressure. We did hundreds of shock experiments with laser-driven flyer plates, measuring time-resolved intensities, spectral shifts and spectral widths with 1 ns time resolution. We also measured the time-dependent strain of the matrix using a fast optomechanical probe. We showed that the QD redshift can measure the strain in the glass or polymer with 1 ns time resolution. In the hard glass above 4 GPa the QDs behave oddly. When the shock arrives, the QDs redshift as the strain increases, but after about 20 ns, the redshift disappears for about 20 ns and then reappears. We think this redshift blinking behavior is related to the shear transients in the matrix, which suggests we might be able to use QDs to measure uniaxial strain and shear.
AB - We have investigated CdSe quantum dots (QDs) as photoluminescent probes of shocked solids. They could be especially useful for composite materials, where the individual components could be tagged with different color QDs. The QDs are tiny (4 nm) spherical emitters, pumped by a continuous laser during shock or diamond anvil experiments up to 12 GPa. In the diamond anvil the QDs are hydrostatically compressed and the emission blueshifts with increasing pressure. By contrast, in shock experiments the QDs are embedded in a hard glass or a soft polymer matrix and subjected to uniaxial compression, which should mechanically deform them, and the emission redshifts with increasing pressure. We did hundreds of shock experiments with laser-driven flyer plates, measuring time-resolved intensities, spectral shifts and spectral widths with 1 ns time resolution. We also measured the time-dependent strain of the matrix using a fast optomechanical probe. We showed that the QD redshift can measure the strain in the glass or polymer with 1 ns time resolution. In the hard glass above 4 GPa the QDs behave oddly. When the shock arrives, the QDs redshift as the strain increases, but after about 20 ns, the redshift disappears for about 20 ns and then reappears. We think this redshift blinking behavior is related to the shear transients in the matrix, which suggests we might be able to use QDs to measure uniaxial strain and shear.
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U2 - 10.1063/1.5044947
DO - 10.1063/1.5044947
M3 - Conference contribution
AN - SCOPUS:85049807196
T3 - AIP Conference Proceedings
BT - Shock Compression of Condensed Matter - 2017
A2 - Knudson, Marcus D.
A2 - Brown, Eric N.
A2 - Chau, Ricky
A2 - Germann, Timothy C.
A2 - Lane, J. Matthew D.
A2 - Eggert, Jon H.
PB - American Institute of Physics Inc.
T2 - 20th Biennial American Physical Society Conference on Shock Compression of Condensed Matter, SCCM 2017
Y2 - 9 July 2017 through 14 July 2017
ER -