The capacity of investigate and tailor the materials properties down to nanoscale created new perspectives for the development of functional devices using single atoms or molecules. Concerning magnetism, the stabilization of magnetic remanence in single atoms represents the ultimate limit on the size reduction of storage devices. After recent advances in this field, lanthanides have emerged as promising candidates for atomic magnets. However, the high diffusion of single standing atoms hinder the development of real-world applications. The next step to further advance towards practical devices is the coordination of these atoms in networks preserving their outstanding magnetic properties. This project will explore the high versatility of molecular linkers to coordinate lanthanides atoms. The combination of state-of-art surface science techniques as scanning tunneling microscopy (STM), non-contact atomic force microscopy, X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) allows a complete investigation of their fundamental properties. It will be possible to unveil the structural, electronic, chemical and magnetic properties of lanthanides networks prepared on different surfaces. The 4f-Mag project aims to find out suitable combinations of surface and molecular linkers to design regular networks of lanthanides maintaining their functionality as single atom magnets and enhancing their remarkable magnetic properties.

The STED project aims at giving an important push to the scientific career of the applicant, in a timely and interdisciplinary topic: imaging the early stages of quantum motion of electrons at their natural space-time scales, i.e., with picometer and attosecond/femtosecond resolutions. The project will take place at IMDEA Nanoscience, a leading multidisciplinary research center dedicated to nanoscience and the development of nanotechnology applications in connection with innovative industries. Electron motion in molecular systems is responsible for natural processes such as photosynthesis, photooxidation, or electronic transport. It is also at the heart of novel technologies based on photovoltaic devices, artificial photosynthesis, molecular wires, etc. Understanding the underlying electron dynamics demands investigating these processes at their natural spatial and temporal scales. In the STED project, I will build a setup where a CW laser and few-femtosecond long laser pulses will be combined with a low-temperature STM. This setup will allow me to image and eventually control electron dynamics occurring in different molecular systems deposited on solid substrates at electronic time scales from hundreds of attoseconds to a few femtoseconds, with simultaneous sub-molecular spatial resolution. I will focus on investigating Rabi oscillations of individual phthalocyanine molecules, and charge-transfer processes between a donor and an acceptor phthalocyanine. The goals are to spectroscopically characterize the induced electron dynamics in real space with the CW laser, and subsequently provide the 'film' of the distribution of the electronic density in real time and real space with the pulsed laser source. This will allow me, e.g., to understand the origin of early sources of decoherences that reduce the efficiency of electronic transport, with possible implications in photovoltaics and quantum information technologies.

Quantitative information on the dynamics and mechanistic principles behind supramolecular systems can be investigated in the single-molecule regime by measuring the nanometer displacements resulting from the application of picoNewton forces in optical trapping (OT) experiments. In particular, the mechanical strength of non-covalent interactions can be quantified when studying the reversible breaking/formation of hydrogen bonds on individual host-guest systems or the switching of a macrocycle between binding stations in a molecular shuttle. However, the fundamental chemical mechanisms behind the obtained real-time operational kinetics are not accessible with OT experiments and fundamental questions about the physicochemical processes underlying real-operation remain unanswered. The goal of this project is to merge OT for single-molecule optical force microscopy experiments with tip-enhaced Raman spectroscopy (TERS). TERS is a powerfull nearfield-based techinque based on the coupling of Raman spectroscopy and scanning probe microscopy. It provides chemical characterization with single molecule sensitivity and few-nm spatial resolution. Since Raman spectroscopy is sensitive to molecular species, inter and intra molecular interactions and orientations; by combining OT-optical force microscopy with TERS, we will access the underlying physicochemical processes triggering specific shuttling events in molecular motors and other types of supramolecular systems. In particular, we aim to create a hybrid tool that can disentangle the relation between mechanical, conformational and chemical properties of individual synthetic supramolecular systems and the non-covalent interactions governing their behavior, with single-molecule sensitivity and spatial resolution in the range of 10 nm. TweeTERS will lead to a major technological improvement in the single-molecule manipulation field and in particular, in the nearly un-explored field of single-molecule supra-molecular chemistry.