Jb. Milan et al., 2-PHOTON RESONANCE-ENHANCED MPI-PES ABOVE THE LOWEST IONIZATION THRESHOLD - OBSERVATION OF THE [A (1)DELTA]5P-PI (2)PHI STATE OF THE SH (SD) RADICAL, Chemical physics letters, 239(4-6), 1995, pp. 326-331
A (2 + 1) resonance enhanced multiphoton ionization photoelectron spec
troscopy (REMPI-PES) study of the hitherto unobserved [a (1) Delta]5p
pi 2 Phi Rydberg state of the SH (SD) radical is reported. Despite the
fact that this state has an excitation energy which exceeds the lowes
t ionization energy, ionization is observed to occur preferentially by
the absorption of a third photon after the two-photon excitation step
, rather than through autoionization. Photoelectron spectra show a lar
ge asymmetry in the rotational branching ratios, which is attributed t
o the high value of Lambda(+) in the ionic state.