Excimer laser multiphoton dissociation of Cr(CO)6: Evidence for two distinct dissociation processes

The excimer laser multiphoton dissociation of Cr(CO)6 has been investigated in the gas phase using emission spectroscopy to detect excited state photoproducts. Following laser irradiation at 193 nm (ArF*), 248 nm (KrF*), and 351 nm (XeF*) well‐resolved Cr(I) emission was detected. The photodissociation mechanism was studied by determining the laser fluence dependence, buffer gas pressure dependence, and temporal profiles of the emission intensity for the various Cr(I) excited states. The data suggest that dissociation occurs via two distinct processes, sequential and direct. The sequential process is found to be extremely sensitive to buffer gas pressure, while the direct mechanism is pressure invariant. The Cr(I) excited state distributions formed in the direct process, following irradiation at the three laser wavelengths used, appear to be statistical.