We describe the fabrication of silicon three dimensional photonic crystals using polymer templates defined by a single step, two-photon exposure through a layer of photopolymer with relief molded on its surface. The resulting crystals exhibit high structural quality over large areas, displaying geometries consistent with calculation. Spectroscopic measurements of transmission and reflection through the silicon and polymer structures reveal excellent optical properties, approaching properties predicted by simulations that assume ideal layouts.

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It is shown that the substantial bonding-energy and work-function changes associated with inert gases adsorbed on metal surfaces arise from an admixture of polar excited configurations that occurs as the excited-state charge-transfer instability is crossed.PACS numbers: 73.20. Hb, 73.30.+y, 78.50 The surprisingly large work-function change caused by rare-gas atoms adsorbed on certain metal surfaces has remained a puzzle since its first observation by Mignolet 1 over a quarter of a century ago. These are among the simplest of adsorbate complexes; they are prototype systems for molecular physisorption, and a failure to understand their properties is a cause for concern when one deals with more complicated molecular adsorbates on which much current attention focuses. Saturation rare-gas coverages can change the work function (p by a volt or more, corresponding to dipole moments of ~0.3 debye/atom. Engel and Gomer 2 and Mignolet, 1 following Mulliken, 3 ascribe this effect to the admixture of polar states; others 4 have discussed adsorbate polarization by the surface field. Ehrlich and Hudda 5 first demonstrated that the bonding energy E a of adsorbed rare gases can also be considerable. Neither E a9 nor the work-function change A 5 ) + adsorbed configurations when the metal work function (p exceeds the adsorbate potential/* for/> 5 s-(/> 5 ) + ionization. This is established in detailed investigations by Cunningham, Greenlaw, and Flynn. 7 A change of only 0.2 eV in

asis state for the complex, with <2 the antisymmetrization operator. Similarly, we write ^' =®ip a f ip m ' for the excited configuration (it is not yet necessary to specify whether or not ip a ' and ty m ' incorporate charge transfer). We assume that ...

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