Optical measurements. For gels, the freshly prepared mixtures of AL-functionalized ITO nanocrystals and organics were injected into home-made glass sandwich cells with 25-micron-thick thermoplastic spacer and sealed with Kapton film (Fig. ). Extinction spectra of both gels and superlattices were measured in transmission using an Agilent Cary 5000 for near-infrared and a Bruker Vertex 70 FTIR for mid-infrared.