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Phenalenyl is a radical nanographene with triangular shape that hosts an unpaired electron with spin S = 1/2. The open-shell nature of phenalenyl is expected to be retained in covalently bonded networks. Here, we study a first step in that direction and report the synthesis of the phenalenyl dimer by combining in-solution synthesis and on-surface activation and its characterization both on Au(111) and on a monolayer of NaCl on top of Au(111) by means of inelastic electron tunneling spectroscopy (IETS). IETS shows inelastic steps that, together with a thorough theoretical analysis, are identified as the singlet-triplet excitation arising from interphenalenyl exchange. Two prominent features of our data permit to shed light on the nature of spin interactions in this system. First, the excitation energies with and without the NaCl decoupling layer are 48 and 41 meV, respectively, indicating a significant renormalization of the spin excitation energies due to exchange with the Au(111) electrons. Second, a position-dependent bias-asymmetry of the height of the inelastic steps is accounted for by an interphenalenyl hybridization of the singly occupied phenalenyl orbitals that is only possible via third neighbor hopping. This hybridization is also essential to activate kinetic interphenalenyl exchange. Our results set the stage for future work on the bottom-up synthesis of spin S = 1/2 spin lattices with large exchange interaction., Comment: 16 pages main manuscript, 4 main figures; supplementary information containing additional data is included

On the wake of the results obtained so far at the SPARC\_LAB test-facility at the Laboratori Nazionali di Frascati (Italy), we are currently investigating the possibility to design and build a new multi-disciplinary user-facility, equipped with a soft X-ray Free Electron Laser (FEL) driven by a $\sim$1 GeV high brightness linac based on plasma accelerator modules. This design study is performed in synergy with the EuPRAXIA design study. In this paper we report about the recent progresses in the on going design study of the new facility.