RESONANCE-ENHANCED MULTIPHOTON IONIZATION SPECTROSCOPY OF THE PF RADICAL

PF radicals in both their ground (X(3) Sigma(-)) and metastable (a 1 D elta) electronic states have been produced by the gas phase reaction o f F atoms with phosphine in a discharge flow reactor and detected by m ass selective resonance enhanced multiphoton ionization (REMPI) spectr oscopy in the wavelength range 410-225 nm. Analysis of the longer wave length end of this spectrum (lambda>328 nm) has enabled identification and spectroscopic characterization of five hitherto unknown Rydberg s tates of this radical. These we label the h(1) Sigma(+) (T-0=57 324.9 cm(-1)), D (3) Delta (T-0=58 223.0 cm(-1)), E (3) Sigma(-)(T-0=58 690 cm(-1)), i 1 Delta (T-0=59 881.6 cm(-1)), and j (1) Sigma(-) (T-0=61 8 73.9 cm(-1)) states, respectively. [Origins, relative to the lowest ro vibrational level of the ground (X (3) Sigma(-)) state are indicated b y the numbers in brackets.] Quantum defect arguments suggest that all five states derive from the electronic configuration [(2) Pi]4p pi(1). Within the shorter wavelength region we identify two additional sets of poorly resolved resonances which we associate with a further two Ry dberg states belonging to series converging to the ground state ioniza tion limit, followed by two extensive progressions of bands. Possible assignments for these two progressions are considered. (C) 1996 Americ an Institute of Physics.