Laser multiphoton ionization and photoelectron spectroscopy of Co(CO)3NO and Fe(CO)5

Abstract

Laser multiphoton dissociation-resonance-enhanced multiphoton ionization (MPD-REMPI) and time-of-flight photoelectron spectra (TOF-PES) of Co(CO)3NO and Fe(CO)5 have been obtained in the range 445–455 nm. The only ions produced by the pulsed dye laser are Co+ and Fe+. Transitions observed in the MPD-REMPI spectra are assigned to resonant states of the neutral atoms. Final states of the atomic ions are determined from the TOF-PES spectra. The multiphoton dissociation process produces metal atoms in a broad distribution of states, ranging in energies up to 33 000 cm−1 for Co, and 32 000 cm−1 for Fe. The most intense REMPI lines are associated with low-lying electronic states (<8500 cm−1 for Fe and Co). By tuning the laser to appropriate wavelengths, neutral metal atoms in selected electronic states may be ionized. At most laser wavelengths, the atomic metal ions are formed in a distribution of states, only some of which are consistent with preservation of the core configuration of the Rydberg intermediate in the ionization step. An exception appears for ionization of Co atoms via 4d Rydberg intermediate states.