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Science 10 August 2007:
Vol. 317. no. 5839, pp. 787 - 790
DOI: 10.1126/science.1145220
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Reports

Ultrafast Flash Thermal Conductance of Molecular Chains

Zhaohui Wang,1* Jeffrey A. Carter,1* Alexei Lagutchev,1* Yee Kan Koh,2 Nak-Hyun Seong,1* David G. Cahill,2,3 Dana D. Dlott1,3{dagger}

At the level of individual molecules, familiar concepts of heat transport no longer apply. When large amounts of heat are transported through a molecule, a crucial process in molecular electronic devices, energy is carried by discrete molecular vibrational excitations. We studied heat transport through self-assembled monolayers of long-chain hydrocarbon molecules anchored to a gold substrate by ultrafast heating of the gold with a femtosecond laser pulse. When the heat reached the methyl groups at the chain ends, a nonlinear coherent vibrational spectroscopy technique detected the resulting thermally induced disorder. The flow of heat into the chains was limited by the interface conductance. The leading edge of the heat burst traveled ballistically along the chains at a velocity of 1 kilometer per second. The molecular conductance per chain was 50 picowatts per kelvin.

1 School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
2 Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
3 Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

* These authors contributed equally to this work.

{dagger} To whom correspondence should be addressed. E-mail: dlott{at}scs.uiuc.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Nuclear Coupling and Polarization in Molecular Transport Junctions: Beyond Tunneling to Function.
M. Galperin, M. A. Ratner, A. Nitzan, and A. Troisi (2008)
Science 319, 1056-1060
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