S. Woutersen et al., RESONANCE-ENHANCED MULTIPHOTON-IONIZATION PHOTOELECTRON-SPECTROSCOPY OF EVEN-PARITY RYDBERG STATES OF ATOMIC SULFUR, Physical review. A, 54(6), 1996, pp. 5126-5132
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.