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For most undergraduate students, introductory quantum chemistry is a challenging subject with many uncommon, if not bizarre, ideas. It is important to relate quantum concepts to the "real" world. Semiconductor quantum dots can be used to introduce and reinforce important points of quantum mechanics and provide real-world applications that exploit quantum phenomena. Most stunning is the colorful demonstration of quantum confinement; few other instances allow direct observation of a quantum effect. Semiconductor nanocrystals can be qualitatively modeled as a particle in a box. This paper presents methods of fabricating nanocrystals, focusing on the pyrolysis of organometallic precursors. The relationship between energy and nanocrystal size is detailed, and the paper closes with an overview of applications of semiconductor nanocrystals.

Aberration-corrected atomic number contrast scanning transmission electron microscopy (Z-STEM) was used to study CdSe nanocrystals prepared using different surfactants. With an optimal probe size of 0.8 Å, unprecedentedly detailed images of the nanocrystal's lattice structure and surface morphology were obtained. This level of detail is important for the characterization of nanomaterials because of the high sensitivity of the nanocrystal's properties to minute changes in structure. As an example of the power of this technique, a sample of CdSe nanocrystals prepared using trioctylphosphine oxide (TOPO) as the surfactant was compared to a sample of CdSe prepared using a mixture of TOPO and hexadecylamine (HDA). Z-STEM reveals striking differences in nanocrystal morphology as the result of the addition of HDA.

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