Reactive adsorbates in on-surface reactions and in heterogeneous catalysis on different substrates are of emerging importance. This is for the crucial roles they take in reaction pathways and for their decisive influence on reaction kinetics. [1] The thermally activated 2D mobility [2] of reaction precursors and reactive adatoms as well as their spatial and temporal coincidence at reaction sites is of mechanistic importance for many interface-specific reactions. In our work, we use the well-studied metalation reaction of H 2 -porphyrins to investigate the action of adatoms on metallic and passivated surface substrates. Porphyrin metalation has been established on atomically clean metallic substrates [3] as well as on metal-oxides [4] and metallic surfaces modified by oxygen [5]. We perform spectro-microscopy correlation experiments combining X-ray Photoelectron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, Low Energy Electron Diffraction and Scanning Tunnelling Microscopy on Cl- and N terminated Cu(001). Thereby we find extended layers of adsorbate-induced superstructures that have decisive and contrasting impact on the reactivity of the surface, as well as on molecular self-assembly. The O and N termination of Cu facilitates the metalation reaction and self-assembled domains of CuTPP are formed at room temperature. Cl termination on the contrary, fully inhibits the metalation reaction and causes 2HTPP to assemble into small ‘magic’ clusters. References [1] Waiz et al., Nature 541, 68–71 (2017). 10.1038/nature20782 [2] Ahsan et al., Nanoscale, 2019, 11, 4895. 10.1021/acs.jpcc.3c03325 [3] Auwärter et al., ChemPhysChem 8 , 250 (2007). 10.1002/cphc.200600675 [4] Wang, C. et al Chem Commun 50 , 8291 (2014). 10.1039/C4CC02919D [5] Nowakowski et al., Chem. Commun. , 49 , 2347 (2013). 10.1039/c3cc39134e [6] Nowakowski et al., ChemistrySelect 2016, 5, 891 –895. 10.1002/slct.201600215 Figure 1

Single layer low-dimensional materials are presently of emerging interest, including in the context of magnetism. In the present report, on-surface supramolecular architecturing was further developed and employed to create surface supported two-dimensional binary spin arrays on atomically clean non-magnetic Au(111). By chemical programming of the modules, different checkerboards were produced combining phthalocyanines containing metals of different oxidation and spin states, diamagnetic zinc, and a metal-free ‘spacer’. In an in-depth, spectro-microscopy and theoretical account, we correlate the structure and the magnetic properties of these tunable systems and discuss the emergence of 2D Kondo magnetism from the spin-bearing components and via the physico-chemical bonding to the underlying substrate. The contributions of the individual elements, as well as the role of the electronic surface state in the bottom substrate, are discussed, also looking towards further in-depth investigations.

In our work, we establish porphin based on-surface architectures which exhibit extraordinary properties e.g. electronic, magnetic and quantum properties originating from the reduced dimensionality of the self-assembled and atomically precise architectures. Unconventional H-bonding as well as the direct site-specific interaction of the porphin’s center metal with the substrate direct the 2D architectures. The coordination and magneto-chemistry of binary 2D assemblies can be investigated by combining scanning probe microscopy / spectroscopy, photoelectron and photoabsorption spectroscopy and density functional theory. Complex electronic [1] and magnetic [2] interactions arise from the 2D periodicity which are also dependent on the state of adsorbed to physisorption and chemical reactivity. Sub-lattices in 2D ‘checkerboard’ architectures of magnetic molecules on magnetic substrates can be selectively switched by chemical ligation [3]. Also we have observed the first example of 2D ferrimagnetic long-range order and remanence for such a 2D architecture on non-magnetic Au(110) [2]. Uniquely, self-assembled 2D architectures contribute to our understanding of fundamental interactions involved in host-guest systems and allow for the specific operation of quantum states with a partial delocalization across the supramolecular on-surface architecture [4]. Thereby we unravel more and more of the on-surface chemistry [5] required to engineer low dimensional materials with unprecedented properties by controlling their architecture. In particular this involves the on-surface supramolecular, the on-surface coordination and the on-surface magneto-chemistry. [1] Lobo-Checa, J. et al., Science 325:300 (2009) [2] Girovsky, J. et al., Nat. Commun., DOI: 10.1038/ncomms15388 (2017). [3] C. Waeckerlin et al, 10.1002/adma.201204274 [4] Nowakowska, S. et al., 10.1021/acsnano.7b07989 [5] Ballav N., et al., JPCL 4:2303 (2013) [4] Figure 1

: The formation of on-surface coordination polymers is controlled by the interplay of chemical reactivity and structure of the building blocks, as well as by the orientating role of the substrate registry. Beyond the pre-determined patterns of structural assembly, the chemical reactivity of the reactants involved may provide alternative pathways in their aggregation. Organic molecules, which are transformed in a surface reaction, may be subsequently trapped via coordination of homo-or heterometal adatoms, which may also play a role in the molecular transformation itself. The amino-functionalized perylene derivative, 4,9-diaminoperylene-quinone-3,10-diimine (DPDI), undergoes specific levels of dehydrogenation (-1 H 2 or -3 H 2 ) depending on the nature of the present adatoms (Fe, Co, Ni or Cu, respectively). In

This thesis focuses on the investigation of on-surface molecular architectures which exhibit extraordinary magnetic and quantum properties originating from the reduced dimensionality at surfaces. Many different combinations of spin-bearing square planar molecules and substrates were used and probed by local techniques as well as by spatial averaging techniques. Probing low-dimensional molecular magnetism by combination of several complementary techniques provides a more complete insight into the subtle interplay of the interactions involved at the surfaces. The comprehensive study of magnetism of Cr-phthalocyanine molecules supported on several different ferromagnetic and non-magnetic substrates demonstrated how the spin state of such molecules depends on the interaction with the substrate. Also in my work I have shown that the relative orientation of the molecule’s and the substrate’s easy magnetization axes is of great importance, even for molecules which are paramagnetic in the bulk. This is further supported by the example of interactions of Cr-based adsorbates with the Au(111) substrate where, for example, a very strong anisotropy of the Cr magnetic moment is observed. At the same time, the exchange coupling interactions with bare ferromagnetic substrates, Co and Ni are different in both the intensity and sign. These observations indicate that a refinement of the current models describing interface magnetism is needed to understand the peculiar magnetic coupling in these systems. Study of various phthalocyanine molecules on Pb(111) demonstrate the importance of employment of X-ray based techniques to complement the local probe investigations of these spin systems coupled to a superconductor. Although such experiments can drive a system out of the superconductive phase by the presence of a magnetic field, it was shown that some magnetic properties of these molecules won’t depend greatly on whether the system is or is not in the superconducting state. This fact is making X-ray based investigations even more important. The emergence of interesting magnetic phenomena through intra- and inter-molecular interactions was addressed next. Pilot experiments performed on triply-fused bisporphyrin molecules opened up the field for a new class of molecules containing two spin centers that can be exchanged providing a plethora of possibilities for tuning the molecule’s magnetic properties. Following up on our recent observation of long range 2D ferrimagnetic ordering in heteromolecular checkerboard assemblies of Fe and Mn phthalocyanine molecules supported on Au(111), we performed the experiments with similar binary 2D systems to further glimpse into the role of 3d orbitals, their symmetries and filling in maintaining long range ordering. It was shown that depending on the configuration and filling of their 3d orbitals the metallo-phthalocyanine molecules will interact by the RKKY interaction or not. In addition, I reported on a significant asymmetry in the mixing of hetero molecular layers that is occurring due to the pinning of one of the molecular types to the surface. Surprisingly this process modifies the layer structure of multilayers and therefore needs to be taken into account for on-surface metalation reactions or for the design of spintronic devices. Further on, different ways of modification of magnetic properties have been investigated. We reported on how spin states of various phthalocyanine molecules can be altered upon exposure to molecular and atomic hydrogen. In the former case, this process is completely reversible, while in the latter case it leads to irreversible changes of both the spin state of the metal center and of the molecule. Also, the ability to induce a Co surface functionalization with both N and Cl adlayers is demonstrated. Here, X-ray Photoelectron Diffraction has been employed to precisely determine interatomic distances in the created functionalized surfaces. In the last part the importance of development of new preparation/characterization techniques is demonstrated. It is shown how we successfully implemented the technique of deposition of large non-sublimable molecules into the UHV directly from solution, and how we have adapted a detector that is commonly used in time-of-flight mass spectrometry for acquiring fast, time-resolved XAS signal at SIM beamline of the SLS. In short, this thesis represents a collection of several pieces of a larger scientific puzzle grazing through several aspects of molecular magnetism.

Realization of long-range magnetic order in surface-supported two-dimensional systems has been challenging, mainly due to the competition between fundamental magnetic interactions as the short-range Kondo effect and spin-stabilizing magnetic exchange interactions. Spin-bearing molecules on conducting substrates represent a rich platform to investigate the interplay of these fundamental magnetic interactions. Here we demonstrate the direct observation of long-range ferrimagnetic order emerging in a two-dimensional supramolecular Kondo lattice. The lattice consists of paramagnetic hexadeca-fluorinated iron phthalocyanine (FeFPc) and manganese phthalocyanine (MnPc) molecules co-assembled into a checkerboard pattern on single-crystalline Au(111) substrates. Remarkably, the remanent magnetic moments are oriented in the out-of-plane direction with significant contribution from orbital moments. First-principles calculations reveal that the FeFPc-MnPc antiferromagnetic nearest-neighbour coupling is mediated by the Ruderman–Kittel–Kasuya–Yosida exchange interaction via the Au substrate electronic states. Our findings suggest the use of molecular frameworks to engineer novel low-dimensional magnetically ordered materials and their application in molecular quantum devices.

The interaction of electrons with a periodic potential of atoms in crystalline solids gives rise to band structure. The band structure of existing materials can be measured by photoemission spectroscopy and accurately understood in terms of the tight-binding model, however not many experimental approaches exist that allow to tailor artificial crystal lattices using a bottom-up approach. The ability to engineer and study atomically crafted designer materials by scanning tunnelling microscopy and spectroscopy (STM/STS) helps to understand the emergence of material properties. Here, we use atom manipulation of individual vacancies in a chlorine monolayer on Cu(100) to construct one-and two-dimensional structures of various densities and sizes. Local STS measurements reveal the emergence of quasiparticle bands, evidenced by standing Bloch waves, with tuneable dispersion. The experimental data are understood in terms of a tight-binding model combined with an additional broadening term that allows an estimation of the coupling to the underlying substrate.

The interaction of electrons with a periodic potential of atoms in crystalline solids gives rise to band structure.The band structure of existing materials can be measured by photoemission spectroscopy and accurately understood in terms of the tight-binding model, however not many experimental approaches exist that allow to tailor artificial crystal lattices using a bottom-up approach.The ability to engineer and study atomically crafted designer materials by scanning tunnelling microscopy and spectroscopy (STM/STS) helps to understand the emergence of material properties.Here, we use atom manipulation of individual vacancies in a chlorine monolayer on Cu(100) to construct one-and two-dimensional structures of various densities and sizes.Local STS measurements reveal the emergence of quasiparticle bands, evidenced by standing Bloch waves, with tuneable dispersion.The experimental data are understood in terms of a tight-binding model combined with an additional broadening term that allows an estimation of the coupling to the underlying substrate.

The presence of N- and Cl-induced superstructures is shown to drastically alter the physicochemical properties of the Cu( 001) substrate. We present coherent evidence that N- and Cl-c(2x2) superstructures on Cu(001) decisively impact the metalation reaction of 5,10,15,20-tetraphenylporphyrin (2HTPP) as well as the on-surface diffusion and assembly of this molecule. The N superstructure facilitates the metalation reaction and self-assembled molecular domains of CuTPP are formed at room temperature (RT). In contrast, the Cl superstructure completely inhibits the self-metalation reaction requiring metal atoms to be deposited from the top and causes 2HTPP to assemble into small clusters. A spectro-microscopy correlation approach combining X-ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS), Low Energy Electron Diffraction (LEED) and Scanning Tunneling Microscopy (STM) has been utilized in this study.

Conceptually very simple optical methods, namely Reflectance Difference Spectroscopy (RDS/RAS) and Differential Reflectance Spectroscopy (DRS), can provide valuable insight into the structure and growth of ultrathin films in straight correlation with their electronic, optical and other physical or chemical properties. Notably, differential optical spectroscopies can achieve sub-monolayer sensitivity and are capable of monitoring kinetic processes on surfaces in real time. This will be illustrated in selected examples dealing with the fabrication and optical characterization of functional layers, such as reconstructed surfaces [1,2], graphene nanoribbons [3], and ultrathin molecular films [4,5]. While the spatial resolution in the UV-VIS range is naturally limited, microscopic information on the structure and electronic properties can be obtained from complementary surface science techniques such as STM and Photoemission Electron Microscopy (PEEM). As an outlook, I will describe how optical spectroscopy and PEEM can be combined into a single experiment, thus enabling truly parallel optical and photoelectron spectroscopy at a local scale.

The magneto-chemical interaction of spin-bearing molecules with substrates is interesting from a coordination chemistry point of view and relevant for spintronics. Unprecedented insight is provided by X-ray photo-emission electron microscopy combined with X-ray magnetic circular dichroism spectroscopy. Here the coupling of a Mn-porphyrin ad-layer to the ferromagnetic Co substrate through suitably modified interfaces is analyzed with this technique.

The formation of on-surface coordination polymers is controlled by the interplay of chemical reactivity and structure of the building blocks, as well as by the orientating role of the substrate registry. Beyond the predetermined patterns of structural assembly, the chemical reactivity of the reactants involved may provide alternative pathways in their aggregation. Organic molecules, which are transformed in a surface reaction, may be subsequently trapped via coordination of homo- or heterometal adatoms, which may also play a role in the molecular transformation. The amino-functionalized perylene derivative, 4,9-diaminoperylene quinone-3,10-diimine (DPDI), undergoes specific levels of dehydrogenation (-1 H2 or -3 H2) depending on the nature of the present adatoms (Fe, Co, Ni or Cu). In this way, the molecule is converted to an endo- or an exoligand, possessing a concave or convex arrangement of ligating atoms, which is decisive for the formation of either 1D or 2D coordination polymers.

We report the discovery of an antiferromagnetic coupling of the magnetic moment of chromium(II) tetraphenylporphyrin (CrTPP) molecules to the magnetization of the clean ferromagnetic Co(001) substrate. We assign this unusual molecule-substrate exchange coupling to the less than half-filled chromium 3d orbitals interacting with Co valence band electrons via porphyrin-ligand molecular orbitals. X-ray magnetic circular dichroism, x-ray photoelectron spectroscopy, and scanning tunneling microscopy are combined with DFT + U calculations and provide evidence for a surprising type of antiferromagnetic 90 degrees indirect magnetic exchange coupling.

On-surface assembly of a spin-bearing and non-aromatic porphyrin-related synthetic Co(II)-complex on a ferromagnetic Ni thin film substrate and subsequent magnetic exchange interaction across the interface were studied by scanning tunnelling microscopy (STM), X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD) and density functional theory +U (DFT + U) calculations.

The paper is focused on presenting possibilities of applying artificial neural networks (ANN) at creating a speed controller of an induction motor drive. The presented method of control takes advantage of approximating properties of multi-layer feedforward networks. The availability of the proposed neurocontroller is verified through the Matlab simulation. The effectiveness of the controller is demonstrated for different operating conditions and motor parameter changes of the drive system.

Amazing ammonia: The molecular spin state of Ni(II) porphyrin, supported on a ferromagnetic Co surface, can be reversibly switched between spin-off (S = 0) and spin-on (S = 1) states upon coordination and decoordination of the gaseous ligand NH3, respectively (see picture). This finding clearly indicates the possible use of the system as a single-molecule-based magnetochemical sensor and in spintronics.

The presence of an oxygen reconstruction on the Cu(001) surface results in the self-metalation of 5,10,15,20-tetraphenylporphyrin (2HTPP) below room temperature (at ~285 K), in contrast to 2HTPP on the bare Cu(001) substrate, where a temperature of ~450 K is required. This study demonstrates the decisive impact of a surface reconstruction on the redox reaction in the solvent-free ultra-high vacuum environment.

A bottom-up approach is introduced to fabricate two-dimensional self-assembled layers of molecular spin-systems containing Mn and Fe ions arranged in a chessboard lattice. We demonstrate that the Mn and Fe spin states can be reversibly operated by their selective response to coordination/decoordination of volatile ligands like ammonia (NH3).

Paramagnetic transition-metal complexes assembled on surfaces are of great interest for potential applications in organic spintronics. The magnetochemical interactions of the spin of the metal centers with both ferromagnetic surfaces and optional axial ligands are yet to be understood. We use a combination of X-ray magnetic circular dichroism (XMCD) and quantum-chemical simulations based on density functional theory (DFT + U) to investigate these metal–organic interfaces with chemically tunable magnetization. The interplay between an optional axial ligand (NO, spin S = 1/2 or NH3, S = 0) and Ni and Co ferromagnetic surfaces affecting the spin of Co(II) tetraphenylporphyrin (d7, S = 1/2), Fe(II) tetraphenylporphyrin (d6, S = 1), Mn(II) tetraphenylporphyrin (d5, S = 5/2) and Mn(II) phthalocyanine (d5, S = 3/2) is studied. We find that the structural trans effect on the surface rules the molecular spin state, as well as the sign and strength of the exchange interaction with the substrate. We refer to this observation as the surface spin-trans effect.

Yttrium hexaboride has the second highest critical temperature, Tc∼8K, among all borides. The presented paper deals with the experimental study of its superconducting energy gap established by the method of the point-contact spectroscopy. The temperature dependence of the energy gap and the strength of the superconducting coupling is presented.