Evidence of registry at the interface during inorganic nucleation at an organic template.

In situ synchrotron x-ray diffraction studies of the nucleation of barium fluoride from supersaturated solutions, at fatty-acid monolayer templates, reveal a commensurate relationship between the interfacial lattices of the organic molecules and the inorganic atoms. At the onset of growth, the barium fluoride layer is very thin and the lateral unit cell is contracted by as much as 4%; at the same time the organic molecules tilt, expanding the organic unit cell. This flexibility is what allows the lattice parameters to be commensurate. Such registry is expected to play an important precursor role in controlled biomineralization and organic-matrix-mediated materials synthesis.