THE PHOTOTRANSFORMATION OF C-60 THIN-FILMS ON GAAS(100) STUDIED BY IN-SITU RAMAN-SPECTROSCOPY

Raman spectra in the region of the pentagonal pinch mode A(g)(2) of C- 60 were taken in situ during the deposition of C-60 on the GaAs(100) s urface at different temperatures. For very low coverages, only the fea ture corresponding to the pentagonal pinch mode of pristine C-60 is vi sible. The onset of polymerization under laser irradiation occurred at thicknesses of about 15 nm which is attributed to a suppressive effec t on the polymerization process due to the interaction of C-60 With th e substrate surface. The line shape for the feature due to photopolyme rized C-60 was different at each temperature indicating distinct polym eric states at different temperatures. These different states are disc ussed in comparison to recent theoretical calculations. Additionally, the photopolymerization due to irradiation after growth was investigat ed in situ. (C) 1998 American Institute of Physics.