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A combination of electron diffraction and infrared reflectance measurements shows that synthetic silica transforms partially into stishovite under high-intensity (GW/cm 2 ) laser irradiation, probably by the formation of a dense ionized plasma above the silica surface. During the transformation the silicon coordination changes from four-fold to six-fold and the silicon-oxygen bond changes from mostly covalent to mostly ionic, such that optical properties of the transformed material differ significantly from those of the original glass. This phase transformation offers one suitable mechanism by which laser-induced damage grows catastrophically once initiated, thereby dramatically shortening the service lifetime of optics used for high-power photonics applications such as inertial confinement fusion.3

Porous ceramics are of great interest for filtration, catalysis, and reactive separation processes. Performance in these applications is highly dependent on features such as pore size distribution and connectivity and wall composition. Here, we describe a method allowing the rational design and synthesis of mesoporous silica composites with controlled heterogeneous pore architectures and demonstrate its validity by producing structures with predetermined placement of regions having different pore size and pore organization.