High-resolution photoelectron spectroscopy of linear ← bent polyatomic photodetachment transitions: the electron affinity of CS2.

A combination of high-resolution velocity-map-imaging photoelectron spectroscopy and isotopic substitution is used to show that precise electron affinities can be obtained from polyatomic photodetachment spectra, even for cases involving significant changes in equilibrium geometry between the molecular neutral and anion. The chosen example CS(2) (X (1)Σ(g)(+)) (linear) ← CS(2)(-) (X (2)A(1)) (bent) photodetachment transition is found to preferentially access highly-excited v(2) (bending) levels of the neutral, with no observation possible of the lowest-v(2) bands. Nevertheless, through (13)C isotopic substitution, the v(2) numbering is established unambiguously and the adiabatic electron affinity of CS(2) is found to be 4456(10) cm(-1) [0.5525(13) eV], by far the most precise value reported to date.