Triamantane was isolated from petroleum, per-fluorinated and the vibrational behaviour investigated by experimental and theoretical methods. Close agreement was found between the experimental and calculated Raman spectrum. The surface vibrational modes are shifted to lower wavenumbers relative to hydrogenated triamantane, due to the increased mass of the surface groups. The Raman spectrum of the fluorinated molecule more closely resembles that of pure diamond compared with hydrogenated triamantane. The absence of a peak at 1150 cm (1) for fluorinated triamantane suggests that this peak, often seen in the spectrum of nanocrystalline diamond, cannot be attributed to vibrations of diamond nanocrystals. (C) 2008 Elsevier B.V. All rights reserved.