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persed in chloroform, protected by the phase-transfer catalyst. Upon addition of 200 lL of PFPE thiol, the nanocrystals aggregated out of chloroform, and could not be dispersed in conventional hydrocarbon-based organic solvents. However, the PFPE-stabilized nanocrystals could readily be dispersed in fluorinated solvents such as Freon and Fluorinert. A miscible antisolvent (ethanol) was added to the nanocrystal dispersion to wash the particles. By centrifuging the nanocrystals, the particles could be collected and redispersed in Freon for further processing or continued washing.Indium manganese arsenide (InMnAs) nanocrystals capped with trioctylphosphine were synthesized using a modification of a previously described synthesis technique [21]. Initially, 0.9 mL of a stock solution of (0.09 M) tristrimethylsilylarsine ([(CH 3 ) 3 Si] 3 As), (0.17 M) indium chloride (InCl 3 ), (0.18 M) manganese bromide (MnBr 2 ), and the coordinating solvent, trioctylphosphine (TOP), was injected into a stainless steel reactor cell in a nitrogen environment. The reaction was carried out at 280 C for 3 h after which the reactor contents were extracted and cleaned by adding excess ethanol and centrifuging. The nanocrystals were further purified by redispersing in chloroform and subsequently precipitating by adding ethanol as an antisolvent.Film Formation: Macroporous films were formed by evaporating~5 lL of dispersion at ambient conditions (22±23 C and~60 % relative humidity) on glassy carbon substrates. High humidity conditions were achieved by placing the glassy carbon substrates in a sealed chamber half filled with water. After allowing adequate time to equilibrate, the nanocrystal dispersion was drop cast on the surface. Dispersions were evaporated inside a glove box under a dry atmosphere (0 % relative humidity); however, they did not produce macroporous structured nanocrystal films.Contact Angle and Interfacial Tension Measurements: Contact angles, h F and h W , were measured using a RamØ-hart Inc. goniometer. A thin layer of gold was evaporated onto a glass slide and then immersed in an ethanol solution of PFPE-thiol (0.5 vol.-%) for 1 h. The slide was then dried overnight. After measuring h F and h W on the as-treated surfaces, the slides were spray-washed with ethanol and Freon and then dried using an air gun. This surface-washing step simulates the excessive exposure of the nanocrystals to antisolvent. The Freon± water interfacial tension was measured using a pendant drop tensiometer consisting of a light source, an optical rail, and a charge coupled device (CCD) camera attached to a software package (KSV Ltd.) to solve the Laplace equation. A drop of Freon was introduced into the continuous aqueous phase using an n-octyltriethoxysilane surface-modified silica capillary (180 lm outer diameter (OD), 50 lm inner diameter (ID)).Characterization: SEM images were acquired on a LEO 1530 SEM equipped with a GEMINI field emission column with a thermal field emitter operating at a 1 kV accelerating voltage. Images were digitally acqu...

A polymer inverse opal with a tunable bandgap is presented. It is shown that, when the opal is infiltrated with a nematic liquid crystal, tuning of the stop band upon the application of an electric field is possible (see Figure for an SEM image of the structure). A discontinuous transition of the λLC shift upon a change in the voltage is observed.

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Laser action in a waveguide configuration has been demonstrated in a planar alignment cell of dye-doped chiral smectic liquid-crystal mixtures with a short pitch helical structure. In this configuration, doped dye can effectively be excited by a pump beam illuminating perpendicularly the helical axis and the laser light emitted along the helical axis propagates in the waveguide. Lasing wavelength can be tuned by adjusting the periodicity of the helical pitch upon applying the electric field.