MULTIPHOTON DISSOCIATION OF IRON CARBONYLS - EMISSION FROM ATOMIC IRON

The third harmonic of the Nd:YAG laser is used to photodissociate Fe(C O)(3)L, where L = C4H6 or C6H8. The resulting emission is analyzed and observed to originate from high lying states of atomic iron. Iron ion s are concurrently produced at laser energies as low as 20 mu J pulse( -1). The nature of the emission spectrum is dependent upon the total p ressure and the nature of any added background gas. The photochemistry is analyzed using an RRKM treatment, which indicates that the absorpt ion of two photons by Fe(CO)(3)L leads to production of FeL with a sma ll excess energy. Ground state Fe production occurs upon absorption of an additional photon. In competition with this process would be the a bsorption of additional photons leading to the observed Fe atomic leve ls with ''intermediate'' energy. High energy states observed in the em ission spectrum could be accessed by absorption of three photons by Fe L. In all three reaction channels, the atomic states could be populate d by multiple curve crossings. Such high levels of excitation are cons tant with the observation of J-independent populations in many of the electronic states and the absence of a Boltzmann temperature for the d istribution of atomic iron electronic states.