  Linear chains made by a single row of sp-hybridized carbon are predicted to
display fascinating mechano-electronic properties connected with their
termination and stabilization inside realistic carbon structures. The present
work describes how the computed vibrational properties of cumulenic and
polyynic carbon chains allow one to interpret the carbynic features observed in
Raman spectra of cluster-assembled sp-sp2 films. The overall picture is
consistent with the measured decay of the sp components induced by air or
oxygen exposure.
