Electron energy loss spectroscopy on alkylated silicon nanocrystals

Alkyl-passivated silicon nanoparticles have been studied via aberration-corrected scanning transmission electron microscopy (STEM) in conjunction with electron energy loss spectroscopy in order to characterize both their chemical composition and structural make-up. Energy loss spectra indicate a predominantly silicon core structure with some oxide species and Si–C surface bonds. Shifts in the Si?L-edge onset to higher energies are attributed to quantum confinement effects in the material although the magnitudes are greater than theoretical values expected for silicon nanocrystals bound by alkyl chains. Nanocrystal STEM samples formed by direct evaporation and deposition of intact nanocrystals show evidence of crystalline planes and structural rearrangements, which can be observed under extended irradiation by the electron probe beam.