Absorption spectra at the carbon K-edge were reported recently for small diamondoid clusters, 108 three of which are investigated here: adamantane, twistane and cubane (in order of increasing steric strain). Strain has an effect on the electronic structure of these clusters that has been investigated with the help of carbon K-edge spectra and simulated spectra are juxtaposed with experimental spectra in Fig. . Note that the state-by-state (eigenstateresolved) approach that is used here is not expected to capture the extended x-ray fine structure, which results from multiple scattering of the outgoing electron, only the near-edge region that is characteristic of covalent bonding.