High-resolution electron momentum spectroscopy of valence satellites of carbon disulfide.

The binding energy spectrum of carbon disulphide (CS(2)) in the energy range of 9-23 eV has been measured by a high-resolution (e,2e) spectrometer employing asymmetric noncoplanar kinematics at an impact energy of 2500 eV plus the binding energy. Taking the advantage of the high energy resolution of 0.54 eV, four main peaks and five satellites in the outer-valence region are resolved. The assignments and pole strengths for these satellite states are achieved by comparing the experimental electron momentum profiles with the corresponding theoretical ones calculated using Hartree-Fock and density functional theory methods. The results are also compared in detail with the recent SAC-CI general-R calculations. General agreement is satisfactory, while the present experiment suggests cooperative contributions from (2)Π(u), (2)Σ(g)(+) states to satellite 2 and (2)Σ(g)(+), (2)Π(g) states to satellite 3. Besides, relatively low pole strength for X (2)Π(g) state is obtained which contradicts all the theoretical calculations [2ph-TDA, ADC(3), SAC-CI general-R, ADC(4)] so far.