Reverse saturable absorption in metal cluster compounds

We report a new family of organometallic compounds that exhibit optical limiting through reverse saturable absorption. The optical limiting properties of the metal cluster compounds HFeCo(3)(CO)(12), [NEt(4)](+)FeCo(3)(CO)(12),(-) HFeCo(3)(CO)(10)(PMe(3))(2) and HFeCo(3)(CO)(10)(P(C(6)H(5))(3))(2) were measured at 532 nm using 8-nsec pulses. Pulse narrowing from 8 to 4 nsec was observed. The data indicate that the optical-limiting properties are essentially independent of the type of counter ion substituted in the compound but dependent on the ligand-type substitution.