UV spectra of iron-doped carbon clusters FeCn n = 3–6

Electronic transitions of jet-cooled FeCn clusters (n = 3–6) were measured between 230 and 300 nm by a mass-resolved 1  + 1 resonant two-photon ionization technique. Rotational profiles were simulated based on previous calculations of ground state geometries and compared to experimental observations. Reasonable agreement is found for the planar fan-like structure of FeC3. The FeC4 data indicate a shorter distance between the Fe atom and the bent C4 unit of the fan. The transitions are suggested to be A32⟵B31 for FeC3 and A51⟵A51 for FeC4. In contrast to the predicted C∞v geometry, non-linear FeC5 is apparently observed. Line width broadening prevents analysis of the FeC6 spectrum.