The photodissociation of mass-selected linear carbon clusters (C-n, n = 4-6
) is studied using fast beam photofragment translational spectroscopy. The
photofragment yield (PFY) spectra consist of several continua spanning the
whole visible and ultraviolet region. The product mass distributions for di
ssociation of C-n clusters are dominated by C-3 and its partner fragment Cn
-3, although some minor channels are also identified for dissociation of C-
4 and C-5 clusters. Translational energy P(E-T) distributions for the C-3 Cn-3 channel were measured at several photolysis energies. The PFY spectra
and P(E-T) distributions indicate that multiphoton dissociation occurs at
photon energies below the dissociation threshold and that both single-photo
n and multiphoton dissociation occur above the threshold. The one-photon co
mponents of the P(E-T) distributions can be modeled by phase space theory (
PST), suggesting that photoexcitation is followed by internal conversion to
the ground state. The PST analysis yields dissociation energies for C-n,--
> C-3 + Cn-3 in reasonable agreement with recent Knudsen effusion mass spec
trometry measurements.