Summary: In the second part of this thesis, we investigate a long standing issue in nanoscience: the efficient emission of light by group-IV nanocrystals. Again, utilizing a combination of optical spectroscopy and theoretical modeling, we are able to attribute long-lived, band-edge photoluminescence from Si nanocrystals to emission from the crystalline core, which remains indirect-gap in character despite substantial quantum confinement. We also attribute rapid, high-energy photoluminescence to a persistent amorphous surface layer. Finally, we explore some of the interesting structural behavior exhibited by group-IV nanocrystals at high pressure.