Reactions with Fe+ with O2 and c-C2H4O are studied by guided ion beam techniques. State-specific reaction cross sections for production of FeO+ are presented for the 6D ground and the 4F first excited states of Fe+. In the reaction with O2, these states exhibit similar cross section energy dependences and magnitudes, in contrast to large differences noted with H2. The dissimilarities are explained in terms of spin and orbital considerations that are much less restrictive in the case of reaction with the triplet O2 molecule. With ethylene oxide, Fe+(6D) reacts endothermically to form FeO+, while Fe+(4F) shows exothermic behavior. The clear difference in cross section behaviors allows a precise determination of D°0(Fe+-O) = 3.53 ± 0.06 eV. This derived value is discussed with respect to several past results. Also presented is reaction of O2 with Fe+ created by laser vaporization. A small fraction of the ions produced by this source is not completely quenched by >105 collisions with He. The extent of this residual electronic excitation is found to be dependent on the power of the vaporizing laser.