The semitrimer picotube is a ring-shaped hydrocarbon closely related to a very short (3,3) carbon nanotube. We study the vibrational properties of the semitrimer by means of Raman spectroscopy and find the structural similarity to nanotubes to be reflected also in the vibrational spectra. In particular, combining polarization-dependent Raman measurements and ab inito calculations we can identify a fully symmetric vibration corresponding to the radial breathing mode in nanotubes. (C) 2007 Elsevier B.V. All rights reserved.