Raman Spectroscopic Study of Iron Pentacarbonyl on Silver at Elevated Temperatures

The thermal reaction of Fe(CO)₅ on evaporated silver films was studied in an atmosphere of argon using Raman spectroscopy. The C-O stretch bands Fe(CO)₅ condensed at 123 K decrease significantly in intensity after 5 min of UV irradiation (254 nm) with no appearance of new bands, but further UV irradiation causes little change in the band intensities, suggesting that a monolayer of Fe(CO)₅ is formed on the surface by the initial UV exposure. Upon heating the sample to 204-213 K without UV irradiation, a distinct Raman spectrum is observed in the v(C-O) region. Heating the sample to 270 K leads to further spectral changes. Possible species and structures which can explain these Raman spectra are discussed.