Abstract
Using time-domain thermoreflectance, we have measured the transport of thermally excited vibrational energy across planar interfaces between water and solids that have been chemically functionalized with a self-assembled monolayer (SAM). The Kapitza length-i.e., the thermal conductivity of water divided by the thermal conductance per unit area of the interface-is analogous to the "slip length" for water flowing tangentially past a solid surface. We find that the Kapitza length at hydrophobic interfaces (10-12 nm) is a factor of 2-3 larger than the Kapitza length at hydrophilic interfaces (3-6 nm). If a vapor layer is present at the hydrophobic interface, and this vapor layer has a thermal conductivity that is comparable to bulk water vapor, then our experimental results constrain the thickness of the vapor layer to be less than 0.25 nm.
Original language | English (US) |
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Article number | 186101 |
Journal | Physical review letters |
Volume | 96 |
Issue number | 18 |
DOIs | |
State | Published - 2006 |
ASJC Scopus subject areas
- General Physics and Astronomy