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Multi-user equipment approved in grant 22/12929-3: ultra-high vacuum cryogenic scanning probe microscope equipped with STM, nc-AFM, and TERS


The joint research project aims to investigate supramolecular and reactive assemblies of on-surface molecular networks/chains with different linker-chemistry controlling the structure and the topology. In addition to the reactive assembly, we shall investigate the emergence of cooperative electron and spin states therein. These systems provide new, tunable alternatives to single graphene sheets or C-nanoribbons. They are ideal model systems to gain deeper insight into the structure-property correlation of isolated sheets, networks, and chains and into their interaction with electronically or spin-interacting substrates. To achieve these aims, the consortium will combine local-probe microscopy/spectroscopy techniques (atomic and single molecular bond resolution) and spatial averaging synchrotron based-spectroscopy, for instance, photoelectron and X-ray absorption spectroscopies, to investigate the assembly and on-surface chemistry of surface supported single sheet/chain materials. We will use selected precursors and substrates to explore i) size-tunable tris-pyridyl-benzene derivatives and ii) linear linkers like 2,7,11,16-tetrabromotetrabenzo[a,c,h,j]phenazine (TBTBP) facilitating covalent chain formation after thermal conversion from double linked coordination chains using different linking coordination centers. Presently, a significant body of work is emerging from the discovery of graphene, C-nanoribbons, and other graphene-related or C-based compounds and their exciting electronic properties. The proposers shall investigate the assembly and characterization of structural analogues toward increased structural and electronic/spin tunability. Specifically, we investigate the tuning of characteristic size/length parameters and dimensionality and compare threefold and fourfold (square planar) symmetry versus linear molecular building blocks. We aim to modify the chemical bonding and the network topology to induce emergent properties like spin-localization, frustration, and new delocalized electronic states and band structures. Supramolecular and coordination chemistry for the engineering of low-dimensional chains and layers/porous networks will be led by the UNICAMP group. Porous networks will be used as scaffolds for on-surface reactions and investigate the site-specific reactivity and shape recognition of different size pores. We will also explore the chemical bonding of the network components and ligands/adsorbates by non-contact atomic force microscopy (nc-AFM) and scanning tunneling microscopy/spectroscopy (STM/STS) in combination with vibrational spectroscopy -- tip-enhanced Raman spectroscopy (TERS) -- obtained with the present instrumentation in the group as well as with the new LT-SPM/TERS machine that shall be acquired within this project. Spectro-Microscopy correlation of tunable low-dimensional materials provided by the UNICAMP partner will be complemented with synchrotron-based techniques from the SLS/PSI and SIRIUS/CNPEM partners. Apart from the scientific case, this project also brings UNICAMP and SIRIUS in SP State to a unique leadership position in nanomaterials science and technology. Thereby tremendous opportunities open up in scientific research and education as the access is shared among experts from six affiliated institutions and comprise a platform for the Ph.D. and Master's students to get exposure in an attractive and application/industry-relevant domain. Last but not least, the project fosters the commissioning and ramp-up phase of SIRIUS. The international level of excellence of the project is a tremendous opportunity for talented students and consolidates the leadership of São Paulo in Brazil and of Brazil in Latin America as the most advanced and technology-geared society. (AU)

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