Using lithographic techniques, we have prepared two-dimensional pores with widths controllable in the range 10- 100 Å. These materials are formed from amorphous superlattices consisting of alternating layers of silicon and silicon dioxide by use of a selective etch. The micropores adsorb hydrocarbons from solution in a size-selective manner. The effects of confinement in these molecular-scale structures are observed by fluorescence spectroscopy: We demonstrate that pyrene molecules trapped in 20-Å pores lack the mobility necessary to form dimers.

• Received 18 August 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.2462