Monitoring the transformation of aliphatic and fullerene molecules by high-energy electrons using surface-enhanced Raman spectroscopy

We report on using 100 keV electrons to obtain amorphous carbon from aliphatic and fullerene molecules, and study this process by monitoring their Raman signal. In this regard, we use self-assembled monolayers of gold nanoparticles to provide high electromagnetic field enhancement, which allows the detection of the Raman signal from even nanometer-thick layers of analyte. Our results show different dynamics in the amorphization process of the two molecules, although both show suppression of their original vibrational resonances even at low exposure doses. We have also used atomic-force microscopy to evaluate the sensitivity of the C60 molecules to electron beams in forming networks of amorphized molecules that are less soluble in the development process. This method allows precise patterning possibilities as well as in situ functionalization of carbonaceous thin films in the perspective of using in electronic device applications.