RESONANCE-ENHANCED MULTIPHOTON-IONIZATION PHOTOELECTRON-SPECTROSCOPY OF EVEN-PARITY RYDBERG STATES OF ATOMIC SULFUR

A (2+1) resonance-enhanced multiphoton-ionization photoelectron spectr oscopy study of the sulfur atom was performed in the one-photon energy region between 260 and 24 nm. Some 20 previously unobserved even-pari ty Rydberg states of the sulfur atom are reported, which were accessed by two-photon transitions from the P-3 ground state of the atom, prep ared by in situ photodissociation of H2S. The (S-4(o))np P-3 series co uld be followed up to n=25. This series is perturbed around n=7 by an interloping Rydberg state converging to the first excited ionic limit D-2(o). A two-channel quantum defect theory analysis was performed in order to estimate the composition of the wave functions of the perturb ed series members, which is compared with the ionic state branching ra tios obtained from photoelectron spectra. This analysis, moreover, ena bled the determination of the ionization energy of the lowest ionic st ate S-4(o) with an improved accuracy as compared to the previously rep orted value.