Extended x-ray-absorption fine structure ͑EXAFS͒, Fourier-transform infrared absorption ͑FTIR͒, and elemental analysis were used on a variety of CdSe nanocrystallites ͑NC's͒ to study surface structure. All CdSe NC's were grown by standard inverse micelle techniques. Two sets of NC's samples were made. One set was made so that only the size of the NC's was varied, while the surface treatment was kept the same. The other set was made so that only the surface treatment was varied, while the size distribution was kept the same. For the EXAFS experiments, reference compounds similar in structure were measured. FTIR found surface Cd atoms to be passivated by pyridines and water groups. Fourier-filtered first-shell Cd EXAFS also supports the existence of water groups attached to the surface Cd atoms. The lack of any SeO and Si(CH 3 ) 3 in the FTIR signal indicates that most surface Se atoms have unterminated bonds. Fourier-filtered first-shell Se EXAFS spectra indicate that Se has only Cd as its first-nearest neighbor, and that the coordination number is reduced from the bulk value, suggesting surface Se atoms are unpassivated. Our data support the existence of surface Se lone-pair orbitals that can trap an optically excited hole. ͓S0163-1829͑97͒00908-9͔

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The ferroelectric polarization of thin films of BaxSr1−xTiO3 is imaged using confocal scanning optical microscopy (CSOM). The thin films are grown by pulsed laser deposition (PLD) on SrTiO3 substrates. Ferroelectric domain structure is imaged by applying a small ac electric field across interdigitated electrodes, and measuring induced reflectivity changes in the film, which are directly related to the polarization. Domain re-orientation is observed by acquiring CSOM images as a function of the dc electric field. Local hysteresis loops are obtained by sweeping the dc electric field at fixed positions on the sample. Micrometer-sized regions exhibit both ferroelectric and paraelectric response, indicating that thermal broadening of the phase transition is largely due to inhomogeneities in the thin films.