Ab initio calculations are used to determine molecular properties of linear carbon clusters Cn (n=3-6) in ground and electronically excited states relative to photodissociation processes. MRD-CI calculations predict that in C3 and C5 the siglet-triiplet splitting between the 1пu and 3пu arising from the same configuration is about 1eV similar as in C2. The energy differences between 1∆g and 1Σ+g corresponding to the same 2g or 2u configuration in C4 and C6 are less than 0.2 eV. Calculations support experimental finding that the energetically most favorable fragmentation channel for linear carbon clusters Cn (n=4-6) corresponds to the loss of C3 to give its partner fragment Cn-3. Further fragmentation channels are discussed.