1. Ultrafast Flash Thermal Conductance of Molecular Chains
by Zhaohui Wang, Jeffrey A. Carter, Alexei Lagutchev, Yee Kan Koh, Nak-Hyun Seong, David G. Cahill, and Dana D. Dlott
Science
Volume 317(5839):
August 10, 2007
Published by AAAS

2. Fig. 1. (A) Concept of the ultrafast flash thermal conductance measurements.
(A) Concept of the ultrafast flash thermal conductance measurements. IR and visible pulses combine to generate SFG in an ∼200-μm-diameter region containing ∼1011 alkane chains. SFG is sensitive to thermal disordering of the alkane terminal methyl groups of SAMs, which occurs when heat propagates from the Au surface to the ends of the alkane chains. (B) Alkanethiol molecule of length h bound to Au surface. (C) Ultrafast thermal reflectance measurements show that the Au layer heats up to 80% of its final temperature in 1 ps. (D) SFG spectra of alkane thiol (n = 17) SAM at ambient temperature (blue) and after an ultrafast temperature increase to 800°C (red).
Zhaohui Wang et al. Science 2007;317:
Published by AAAS

3. Fig. 2. Results of molecular simulations of alkanethiol SAMs
Fig. 2. Results of molecular simulations of alkanethiol SAMs. (A) Structure of alkanethiol SAM (n = 15).
Results of molecular simulations of alkanethiol SAMs. (A) Structure of alkanethiol SAM (n = 15). Simulations were performed on a unit cell of 27 alkanes with periodic boundary conditions. When T is increased to a high temperature, the methyl head groups become orientationally disordered. (B) The SFG intensity for the νsCH3 transition is approximately proportional to the square of the normalized ensemble–average IR dipole moment (〈μ〉/μIR)2, which is temperature dependent. (C) With an instantaneous temperature jump to 1100 K, the methyl head groups become orientationally disordered in less than 2 ps.
Zhaohui Wang et al. Science 2007;317:
Published by AAAS

4. Fig. 3. (A) SFG spectra of C8 (n = 7) and C18 (n = 17) SAMs without heating pulses (blue) and with flash-heating to 800°C (red).
(A) SFG spectra of C8 (n = 7) and C18 (n = 17) SAMs without heating pulses (blue) and with flash-heating to 800°C (red). (B) VRF for a C8 monolayer. (C) VRF for a C18 monolayer.
Zhaohui Wang et al. Science 2007;317:
Published by AAAS

5. Fig. 4. (A) Dependence on chain length of the delay time t0 between the flash-heating pulse and the arrival of the initial burst of heat at the methyl head groups.
(A) Dependence on chain length of the delay time t0 between the flash-heating pulse and the arrival of the initial burst of heat at the methyl head groups. (B) Dependence on chain length of the time constant τ for thermal equilibration between flash-heated Au and alkane chains.
Zhaohui Wang et al. Science 2007;317:
Published by AAAS