A molecular 'salve' to soothe surface stresses

NIST researchers measured the surface stress of a monolayer film on gold by measuring the changing curvature of a gold-coated glass cantilever as molecules of mercaptobenzoic acid were deposited on... Click here for more information.

Researchers at the National Institute of Standards and Technology (NIST) have shown for the first time that a single layer of molecular “salve” can significantly soothe the stresses affecting clean metal surfaces. The discovery, revealed in a new paper,* may help scientists to understand the factors that influence surface stress, which is important in a broad array of applications from chemical and biological sensors to semiconductor manufacturing and metal plating.

Because the atoms on a clean metal surface are not bound on all sides, they are much more strongly bonded to each other than to the atoms beneath them. Atoms in a block of metal are like a big family, relaxed when surrounded by kinfolk. But when the metal is cut, the atoms exposed at the surface cling tighter to the siblings at their sides and draw closer together. That creates surface stress and causes the edges to curl and pull in toward the center of the surface.