PHOTOIONIZATION DYNAMICS AND CHARGE SEPARATION REACTIONS OF IRON PENTACARBONYL, ENNEACARBONYL, AND DODECACARBONYL COMPLEXES INDUCED BY PHOTOABSORPTION IN THE 20-90 EV ENERGY-RANGE

The results of a study of the photoionization dynamics of iron penta-, ennea-, and dodecacarbonyl complexes are presented. In these experime nts the gaseous iron carbonyl complexes are ionized via absorption of photons in the 20-90 eV energy range. Ionic products are analyzed usin g time-of-flight mass spectrometry. Cation pairs formed via double ion ization of the iron carbonyl complexes are analyzed using photoion-pho toion coincidence techniques. Photoion pairs corresponding to a direct two-body charge separation of high-mass iron carbonyl dications, such as CO+/Fe(CO)(n)(+), with n greater than or equal to 3, could not be detected. However, several ion pairs, such as C+/Fe(CO)(n)(+), with n = 0, 1, and CO+/Fe(CO)(n)(+), with n = 0, 1, have been observed genera ted by charge separation reactions originating from doubly charged iro n carbonyl fragments. The total photoionization efficiency decreases g radually in the studied energy range between 20 and 90 eV, although a broad relative maximum in the photoionization efficiency is observed f or iron pentacarbonyl around 60 eV photon energy, This relative maximu m is attributed to an increased ionization efficiency caused by the ir on 3p inner shell resonant excitation.