Fig. 4. FT-LIED retrieval of OCS⁺ structure.

a Differential cross-section (DCS; blue dashed line) as a function of returning kinetic energy corresponding to electrons detected in coincidence with OCS⁺. A linear regression filter (black starred line) is applied to the DCS to extract the incoherent sum of atomic scatterings, I_A. The area of uncertainty is given by the longitudinal detected momentum error (red horizontal) and the statistical error based on a Poissonian distribution (blue vertical). b The molecular contrast factor (MCF), defined by I_M/I_A, as a function of momentum transfer. c Radial distribution (black dashed line) obtained by the Fourier transform (FT) of the MCF distribution shown in (b). The resulting FT spectrum contains three clear peaks corresponding to the C–O, C–S and O–S internuclear distances. The uncertainty in the measured peaks is indicated by the black dotted vertical lines (see supplementary note 2). A schematic of the retrieved asymmetrically stretched and bent OCS⁺ structure is shown in the inset.