Credit: Mark Losego
Graphic detailing how heat flux (flow) is measured at the atomic scale. The image at the bottom shows the quartz substrate and thin gold film that make up two parts of the measurement system. What isn’t seen is the molecular monolayer between them that consists of millions of molecular chains each 12 carbon atoms long. The monolayer serves as the interface between the quartz and the gold film.
The inset on top focuses on two of the molecular chains in the monolayer—one capped by a methyl group (large green sphere atop the left chain) and the other by a thiol group (large red sphere atop the right chain). When heat is applied to the gold film, it causes the chains to oscillate. The weaker-bonding methyl capped chain (left) transfers heat slower than its stronger-bonding thiol capped counterpart (right).