Time-resolved IR diode laser spectroscopy: Kinetics and product distribution determination of transient photoproducts formed by UV excimer laser photolysis of irony pentacarbonyl

Time-resolved IR spectroscopy (TRIS) is employed to identify and study the iron carbonyl and CO photofragments of UV photolyzed Fe(CO){dollar}sb5{dollar}. Photofragment reactions with Fe(CO){dollar}sb5{dollar} result in the formation of dinuclear and polynuclear species, some with reaction cross-section on the order of single collisions. Reactions taking place orders of magnitude more slowly are consistent with spin forbidden processes.; Addition of a tunable IR diode laser as the probe source for the TRIS experiments has advantages over a conventional CO laser probe source including a wider tuning range, better long timescale stability and the ability to tune off vibrationally and rotationally excited CO. The IR diode laser permits observation of polynuclear species absorbing at {dollar}>{dollar}2040 cm{dollar}sp{lcub}-1{rcub}{dollar}, measurement of the concentration of vibrationally excited CO and a much higher resolution analysis of the iron carbonyl absorptions.; A number of previously unknown species as well as species observed for the first time in the gas-phase have been detected. TRIS assignments were made for the mononuclear iron carbonyl species: Fe(CO) and excited states of Fe(CO){dollar}sb3{dollar} and Fe(CO){dollar}sb4{dollar}. Assignments for observed dinuclear species included: Fe{dollar}sb2{dollar}(CO){dollar}sb6{dollar}, Fe{dollar}sb2{dollar}(CO){dollar}sb7{dollar}, multiple isomers of Fe{dollar}sb2{dollar}(CO){dollar}sb8{dollar} and two isomers of Fe{dollar}sb2{dollar}(CO){dollar}sb9{dollar}. Formation of Fe{dollar}sb3{dollar}(CO){dollar}sb{lcub}12{rcub}{dollar} was also observed. Reaction rates for these processes as well as for Fe(CO){dollar}sb4{dollar} + O{dollar}sb2{dollar} and Fe(CO){dollar}sb4{dollar} + H{dollar}sb2{dollar} are reported.; Quantitative distributions of photoproducts produced following 193, 248 and 351 nm photolysis were obtained. Approximate distributions of excited Fe(CO){dollar}sb4{dollar}* formed on 351 nm and excited Fe(CO){dollar}sb3{dollar}* formed on 248 nm photolysis were measured and are reported. A qualitative CO photoproduct distribution was also measured and is reported. The photofragment and CO product distribution measured in this study are compared to those measured in prior molecular beam studies of the photodissociation of Fe(CO){dollar}sb5{dollar}.