measuring heat flow across molecules

[phantom power]

(Just the fact that these guys are measuring things in picoseconds, and at the scale of individual molecules, kind of blows my mind.)

"The flow of vibrational energy across a molecule is dependent upon where and how the energy is deposited," said Dana Dlott, a professor of chemistry at Illinois and a co-author of a paper to appear in the journal Science, as part of the Science Express Web site, on Sept. 23. "Unlike normal heat conduction, different excitations may travel across the molecule along different paths and at different rates."

To monitor energy flow, Dlott and his colleagues – Scranton chemistry professor John Deak, Illinois postdoctoral research associate Zhaohui Wang and graduate student Yoonsoo Pang, and Scranton undergraduate student Timothy Sechler – used an ultrafast laser spectrometer technique with picosecond time resolution.

The system the scientists studied is called a reverse micelle, and consisted of a nanodroplet containing 35 water molecules enclosed in a sphere of surfactant (sodium dioctyl sulfosuccinate) one molecule thick that was suspended in carbon tetrachloride. The ultrafast laser technique, developed at Illinois, monitored vibrational energy flow as it moved from water, through the surfactant shell out to the organic solvent, atom by atom.

When the researchers deposited energy in the nanodroplet, the vibrations moved through the surfactant and into the carbon tetrachloride within 10 picoseconds. However, when the energy was deposited directly into the surfactant, the vibrations required 20 to 40 picoseconds to move into the carbon tetrachloride. Even though the distance was shorter, the energy transfer took significantly longer.

http://www.sciencedaily.com/releases/2004/09/040928101621.htm

[EST]

1. This could have a tremendous impact on rocket design,

as well as space thruster efficiency as regards ever higher thrust particulate acceleration. Rides to Mars, anyone?