Although, ferrous hemeproteins dynamics and ligand photodissocn. pathways has been discussed, less is known about the ferric hemeproteins photophys. processes. Recently, ultrafast timescale measurements of ferric HbICN (Hb I from L. pectinata) and MbCN complexes indicated the presence of a short-lived absorption signal, which developed into a red shifted Soret band and decays to zero with time const. in 3.6 ps. Data presented here on ferric HbINO, HbIN3, HbIH2S and metHbI and ferrous HbICN and HbINO complexes suggest a mechanism for the photoinduce redn. of ferric HbI species. After photoexcitation the ferric HbINO, HbIN3, HbIH2S and metHbI species exhibit an absorption transient formation near .apprx.435 nm which was formed in fi300 fs. Time decays fluctuated from 4.5 ps to 6 ps. More than 95 % of signal recovery was obsd. within 20 ps after photoexcitation. These transient appears to be similar to that obsd. to a reduced specie in ferrous species. The formation of a transient specie at 430 nm in the ferric derivs. and the subsequent ultrafast measurements ferrous HbIO2, HbINO, and HbICN species led to the suggestion that the data can be explained by photoinduced redn. of the HbI Fe(III) derivs. To det. the formation of HbI ferrous species a series of transient absorption spectra were obtained from the ferric species in the presence of carbon monoxide. Spectral displacement obsd. in UV-VIS spectrum confirmed the formation of the HbICO complex and suggests that the photoinduced ferrous species has similar structural and chem. properties as deoxy HbI. This phenomenon was obsd. when the sample was exposed to power ranging from 10 gJ to 0.3 gJ, showing a population dependency with power intensities. [on SciFinder (R)]