  Surface Enhanced Raman Spectroscopy (SERS) is exploited here to investigate
the interaction of isolated sp carbon chains (polyynes) in a methanol solution
with silver nanoparticles. Hydrogen-terminated polyynes show a strong
interaction with silver colloids used as the SERS active medium revealing a
chemical SERS effect. SERS spectra after mixing polyynes with silver colloids
show a noticeable time evolution. Experimental results, supported by density
functional theory (DFT) calculations of the Raman modes, allow us to
investigate the behavior and stability of polyynes of different lengths and the
overall sp conversion towards sp2 phase.
