This paper reports the results of a study of adsorption of small molecules on the surface of buckminsterfullerene, C60 and on single walled carbon nanotubes (SWNT). The pressure dependence of the Raman spectrum was investigated over the range 0-100 kbar in methanol-water mixtures that were used as the pressure-transmitting-fluid (PTF) in a diamond anvil cell. It is found that the spectral shift and its pressure derivative are sensitive to both the applied pressure and to the composition of the PTF. These observations are consistent with an explanation that involves preferential adsorption onto the surface of the C/sub 60/. In particular, the notion of C60 collapse need not be invoked to explain the observations.