Pulsed-field ionization zero-kinetic-energy photoelectron spectra of Ar-2

The pulsed-field ionization (PFI) zero-kinetic-energy (ZEKE) photoelectron spectra of Ar, were measured between 117 000 cm(-1) (14.5 eV) and 128 300 c m(-1) (15.9 eV) using the penetrating field technique and synchrotron radia tion at resolutions of up to 1 meV. The A(2)Sigma(1/2u)(+) ground state and B(2)Pi(1/2g) and C(2)Pi(3/2u) excited states were assigned to those spectr a. The first adiabatic ionization potential of Ar, was determined to be 14. 4572 +/- 0.0007 eV. A Le Roy-Bernstein plot and a Birge-Sponer plot were us ed to determine the dissociation Limit of the A2 Sigma(1/2u)(+) ground stat e. The vibrational level of the C(2)Pi(3/2u) excited state was observed for the first time. The effective lifetime for high-n Rydberg states convergin g on the vibrational levels of the C(2)Pi(1/2u) excited state is estimated to be shorter than those of the A(2)Sigma(1/2u)(+) B(2)Pi(1/2g), and C(2)Pi (3/2u) states, because the spectrum could not be observed on the PFI-ZEKE e xperiment. The threshold photoelectron-photoion coincidence spectra of Ar, were also measured and compared with the spectra obtained from the PFI-ZEKE experiment, (C) 1999 Academic Press.