Sabine Maier

• Professor
• Professor (Associate) at Friedrich-Alexander-University Erlangen-Nürnberg

The self-assembly of pyridyl-functionalized triazine (T4PT) was studied on Au(111) using low-temperature scanning tunneling microscopy (STM) under ultra-high vacuum conditions combined with density functional theory (DFT) calculations. In particular, we investigated the effect of temperature on the intermolecular interactions within the assemblies....

The [n]cycloparaphenylenes ([n]CPPs)—npara-linked phenylenes that form a closed-loop—have attracted substantial attention due to their unique cyclic structure and highly effective para-conjugation leading to a myriad of fascinating electronic and optoelectronic properties. However, their strained topology prevents the π-extension of CPPs to convert...

Cleaving single crystals in situ under ultra-high vacuum conditions provides a reliable and straightforward approach to prepare clean and atomically well-defined surfaces. Here, we present a versatile sample cleaver to efficiently prepare ionic crystal surfaces under ultra-high vacuum conditions, which is suitable for preparation of softer material...

The adsorption and self-assembly of a Zn-tetraphenylporphyrin derivative (Zn-pCNTPP) with a cyano group was investigated on KBr(001) and MgO(001) using low-temperature non-contact atomic force microscopy (nc-AFM) combined with dispersion-corrected density-functional theory (DFT). The deposition of Zn-pCNTPP at submonolayer coverage leads on both su...

Over the past two decades, organic molecules adsorbed on atomically defined metal surfaces have been intensively studied to obtain an in-depth understanding of their self-assembly behavior, on-surface reactivity, as well as their structural and electronic properties [1-6]. An important aspect to unravel their potential use in electronic and optoele...

The post-synthetic modification of covalent organic frameworks (COFs) via host-guest chemistry is an important method to tailor their electronic properties for applications. Due to the limited structural control in the assembly of two-dimensional surface-supported COFs, supramolecular networks are traditionally used at present for host-guest experi...

Graphyne-based two-dimensional (2D) carbon allotropes feature extraordinary physical properties; however, their synthesis as crystalline single-layered materials has remained challenging. We report on the fabrication of large-area organometallic Ag-bis-acetylide networks and their structural and electronic properties on Ag(111) using low-temperatur...

Demonstrated here is a supramolecular approach to fabricate highly ordered monolayered hydrogen‐ and halogen‐bonded graphyne‐like two‐dimensional (2D) materials from triethynyltriazine derivatives on Au(111) and Ag(111). The 2D networks are stabilized by N⋅⋅⋅H−C(sp) bonds and N⋅⋅⋅Br−C(sp) bonds to the triazine core. The structural properties and th...

On‐surface assembly of hydrogen‐ and halogen‐bonded supramolecular graphyne‐like networks from functionalized triethynyltriazine derivatives on metal surfaces, Au(111) and Ag(111), are described. The networks are stabilized by N⋅⋅⋅H−C(sp) bonds and N⋅⋅⋅Br−C(sp) bonds to the triazine core. Abstract Demonstrated here is a supramolecular approach to...

Combining organic synthesis with microscopy addresses long-standing bottlenecks in cyclocarbon production

We report on the influence of the surface structure and the reaction kinetics in the bottom‐up fabrication of porous nanoribbons on silver surfaces using low‐temperature scanning tunneling microscopy. The porous carbon nanoribbons are fabricated by the polymerization of 1,3,5‐tris(3‐bromophenyl)benzene directly on the Ag surface using an Ullmann‐ty...

The coordination-restricted ortho-site C–H bond activation and dehydrogenative homocoupling of 4,4’-(1,3-phenylene)dipyridine (1,3-BPyB) and 4,4’-(1,4-phenylene)dipyridine (1,4-BPyB) on different metal surfaces were studied by a combination of scanning tunneling microscopy, non-contact atomic force microscopy and density functional theory calculati...

Zig-zag nanographenes are promising candidates for the applications in organic electronics due to the electronic properties induced by their periphery. However, the synthetic access to these compounds remains virtually unexplored. There is a lack in efficient and mild strategies origins in the reduced stability, increased reactivity, and low solubi...

The structure and growth of water films on surfaces is reviewed, starting from single molecules to two-dimensional wetting layers, and liquid interfaces. This progression follows the increase in temperature and vapor pressure from a few degrees Kelvin in ultra-high vacuum, where Scanning Tunneling and Atomic Force Microscopies (STM and AFM) provide...

Based on scanning tunneling microscopy experiments combined with density functional theory, we report the formation and the electronic structure of porous binary supramolecular networks on Au(111). The two triphenylamine derivatives...

The fabrication of long-range ordered 2D polymers directly on metal surfaces still presents a great challenge in ultra-high vacuum surface science. The structure of the polymer networks is in general predetermined by the coupling chemistry and the symmetry of the molecular precursors. However, the irreversible nature of the C–C coupling reaction re...

The electronic structure of surface-supported organometallic networks with Ag-bis-acetylide bonds that are intermediate products in the bottom-up synthesis of graphdiyne and graphdiyne-like networks were studied. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal a frontier, unoccupied electronic state that is delocalized along the e...

The syntheses of five 1D coordination polymers containing the sawhorse type unit [Ru₂(μ-OAc)₂(CO)₄] linked by various bridging N,N donor ligands are reported. Various π-conjugated linker such as trans-1,2-bis(N-methyl)imidazol-2-yl)ethylene (trans-bie), pyrazine (pyz), 4,4'-bipyridine (4,4'-bipy) and 1,2-di(4-pyridyl)ethylene (bpe) as well as aliph...

We demonstrate the on-surface synthesis of porous carbon nanoribbons on Ag(111) via a preprogrammed isomerization of conformationally flexible polymer chains followed by dehydrogenation reactions using thermal annealing. The carbon chains are fabricated by the polymerization of the prochiral 1,3,5-tris(3-bromophenyl)benzene (mTBPB) precursors direc...

The fabrication of nanostructures in a bottom-up approach from specific molecular precursors offers the opportunity to create tailored materials for applications in nanoelec-tronics. However, the formation of defect-free two-dimensional (2D) covalent networks remains a challenge, which makes it difficult to unveil their electronic structure. Here w...

Supplementary Figures, Supplementary Discussion, Supplementary Methods and Supplementary References.

The synthesis of non-conjugated, carbon-rich building blocks is described, based on a basic scaffold of triethynylmethanol (TEtM). The substitution of the ethynyl groups can be easily varied (including R3Si, H, Br), and this allows structural tuning for stabilization, synthetic derivatization, and adsorption on Ag(111) or Au(111). X-ray crystallogr...

Scanning tunneling microscopy was used to probe the structure and growth of the first few layers of water on Ru(0001) and Pt(111) at the molecular level. The surface-bound first layer is composed of a mixture of water molecules forming hexagonal structures, both in registry and out-of-registry with the substrate atoms. The hexagons are connected by...

Water is the most abundant molecule on Earth's surface with interesting physical properties, which arise as a consequence of its ability to form hydrogen-bond networks. Water and its dissociation products play an important role in electrochemistry, corrosion, environmental chemistry, and heterogeneous catalysis. Water molecules at the interface wit...

This chapter reviews friction force microscopy experiments that reveal atomic-scale processes in single asperity contacts during sliding. Different regimes of atomic friction will be discussed including smooth sliding with low dissipation and the dissipative atomic stick–slip motion, where the tip jumps from one lattice site to the next. Furthermor...

The adsorption, chemical nature, and self-assembly of diaminotriazinyl- and carboxyl-substituted triphenylamines with dimethylmethylene bridges were studied on Au(111) and Cu(111) at submonolayer coverage by low-temperature scanning tunneling microscopy and density functional theory. On Au(111), both molecules form extended porous honeycomb network...

The adsorption and reactions of water on surfaces has attracted great interest, as water is involved in many physical and chemical processes at interfaces. On metal surfaces, the adsorption energy of water is comparable to the hydrogen bond strength in water. Therefore, the delicate balance between the water–water and the water–metal interaction st...

We study the mechanism leading to the breaking of the N-H bonds in ammonia on Ru(0001) by means of scanning tunneling microscopy (STM). Our results support a model where injection of electrons or holes into antibonding (LUMO) and bonding (HOMO) orbitals of the molecule is far more effective than thermal excitations for molecular dissociation. We al...

We present a technique to pattern the charge density of a large-area epitaxial graphene sheet locally without using metallic gates. Instead, local intercalation of the graphene-substrate interface can selectively be established in the vicinity of graphene edges or predefined voids. It provides changes of the work function of several hundred meV, co...

Graphene grown on Rh(111) was used as a template for the growth of Pd nanoclusters. Using high-resolution synchrotron radiation-based X-ray photoelectron spectroscopy, we studied the deposition of Pd on corrugated graphene in situ. From the XP spectra, we deduce a cluster-by-cluster growth mode. The formation of clusters with 3 nm diameter was conf...

We have studied the mechanism of the partial dissociation of water on Ru(0001) by high resolution scanning tunneling microscopy (STM). The thermal evolution of water at submonolayer coverage has been tracked in the 110-145 K temperature range to identify the precursor structures for the partial dissociation. These were found to consist of hexagons...

Conformational changes in the conjugated backbone of poly- and oligodiacetylenes (PDAs and ODAs) play an important role in determining the electronic properties of these compounds. At the same time, conformational changes can also result in a folded structure that shows helical chirality. Using D-camphor as a chiral building block, we have designed...

Konformationsänderungen des konjugierten Rückgrats von Poly- und Oligodiacetylenen (PDAs und ODAs) spielen bei der Bestimmung der elektronischen Eigenschaften dieser Verbindungen eine wichtige Rolle. Gleichzeitig können Konformationsänderungen auch zu gefalteten Strukturen führen, die helikale Chiralität aufweisen. Durch Verwendung von D-Campher al...

We present a fabrication process for freely suspended membranes consisting of bi- and trilayer graphene grown on silicon carbide. The procedure, involving photo-electrochemical etching, enables the simultaneous fabrication of hundreds of arbitrarily shaped membranes with an area up to $500$\,\textmu m$^2$ and a yield of around 90 percent. Micro-Ram...

The adsorption and dissociation of ammonia on Ru(0001) was studied by scanning tunneling microscopy (STM), density functional theory (DFT), and STM contrast simulations. Various NHx (with x = 0–2) species were formed by controlled STM tip manipulation. Each species shows a characteristic imaging contrast in STM measurements, changing from a protrus...

High-resolution scanning tunneling microscopy (STM) reveals that the first layer of water on Ru(0001) and also on Pd(111) consists of hexagonal molecular domains of two types, rotated by 30∘ relative to one another. Pentagon and heptagon clusters bridge the two types of hexagons. One of the orientations is in registry with the substrate. Its molecu...

The adsorption and reactions of small molecules, such as water and oxygen, with graphene films is an area of active research, as graphene may hold the key to unique applications in electronics, batteries, and other technologies. Since the graphene films produced so far are typically polycrystalline, with point and line defects that can strongly aff...

We present a combined scanning tunneling microscopy (STM) and density functional theory (DFT) study of the adsorption of water on a Ru(0001) surface covered with half monolayer of oxygen. The adsorption of water causes a shift of half of the oxygen atoms in the O(2x1) structure from hcp sites to fcc sites, creating a honeycomb structure where water...

Atomic force microscopy (AFM) and scanning tunneling microscopy (STM) are well established techniques to image surfaces and to probe material properties at the atomic and molecular scale. In this review, we show hybrid combinations of AFM and STM that bring together the best of two worlds: the simultaneous detection of atomic scale forces and condu...

We review recent friction measurements on ordered superstructures performed by atomic force microscopy. In particular, we consider ultrathin KBr films on NaCl(001) and Cu(001) surfaces, single and bilayer graphene on SiC(0001), and the herringbone reconstruction of Au(111). Atomically resolved friction images of these systems show periodic features...

Low-temperature scanning tunneling microscopy and density-functional theory (DFT) were used to study the adsorption of water on a Ru(0001) surface covered with half monolayer of oxygen. The oxygen atoms occupy hcp sites in an ordered structure with (2×1) periodicity. DFT predicts that water is weakly bound to the unmodified surface, 86 meV compared...

Low-energy electron microscopy (LEEM) reveals a new mode of graphene growth on Ru(0001) in which Ru atoms are etched from a step edge and injected under a growing graphene sheet. Based on density functional calculations, we propose a model wherein injected Ru atoms form metastable islands under the graphene. Scanning tunneling microscopy (STM) reve...

The initial stages of water adsorption on the Pd(111) and Ru(0001) surfaces have been investigated experimentally by scanning tunneling microscopy in the temperature range between 40 and 130 K, and theoretically with density functional theory (DFT) total energy calculations and scanning tunneling microscopy (STM) image simulations. Below 125 K, wat...

Tip-induced deformations of meso-(4-cyanophenyl)-substituted Zn(II) porphyrin molecular wires self-assembled on KBr(001) were studied by frequency modulation dynamic force microscopy. Since the wires are weakly bonded to the KBr substrate and to the neighboring molecules, they can easily be cut by the scanning tip. We found that the damaged molecul...

Atomic-scale friction between a sharp tip at the end of a micro-fabricated silicon cantilever and atomically flat surfaces (NaCl, KBr, HOPG and mica) can be significantly reduced by piezo-induced perpendicular mechanical oscillations at specific resonance frequencies of the cantilever in gentle contact with the sample. The reported measurements con...

The friction between an atomically sharp tip and a solid surface (NaCl and highly oriented pyrolytic graphite) is analyzed theoretically in the framework of a modified Tomlinson model in two dimensions. Lateral forces are studied as a function of temperature, load, and magnitude of actuation. The actuation leads to a reduction in friction and allow...

We discuss how various forms of dry superlubricity, recently observed on the nanoscale, have been interpreted by simple phenomenological models. In particular, we review the cases of static and dynamic single-contact lubricity, thermolubricity, and structural lubricity. All these phenomena have been studied by friction force microscopy and explaine...

Well-ordered nanostructures of meso-substituted Zn(II) molecular porphyrin wires were formed along step edges and specific directions of KBr(001). These multiwires are found to be mainly oriented along the direction of the KBr substrate, while on unannealed KBr substrates, wires with various orientations are observed. The molecule-to-molecule dista...

Combined atomic and friction force microscopy reveals a significant modulation of atomic-scale friction related to the small periodic rumpling induced at the interface between heteroepitaxial films of KBr on NaCl(100). Transitions from dissipative atomic-scale stick slip to smooth sliding with ultralow friction are observed within the 6×6 surface u...

Atomic stick-slip experiments on the KBr(100) surface are analyzed using classical zero temperature atomistic simulations. Three different tip models exhibiting atomic stick-slip movement are studied in comparison with the experimental data and the Tomlinson model. The implications of a compliant tip apex for the stick-slip process and the dissipat...

Ultrathin well-ordered films of KBr on NaCl(100) and of NaCl on KBr(100) have been grown. The films were imaged by means of noncontact atomic force microscopy with atomic resolution under ultrahigh vacuum conditions. An extreme asymmetry in the structure of the interface was found for the two systems. The first layer of KBr on NaCl(100) grows with...

The formation of molecular wires on a nanostructured KBr(001) substrate is observed by non- contact atomic force microscopy. Locally polarized cyano porphyrin molecules evaporated on this sample assemble in a linear fashion along straight pit edges forming one dimensional structures.

Stiction and wear are demanding problems in nanoelectromechanical devices, because of their large surface-to-volume ratios and the inapplicability of traditional liquid lubricants. An efficient way to switch friction on and off at the atomic scale is achieved by exciting the mechanical resonances of the sliding system perpendicular to the contact p...

For the first time, ordered polar molecules confined in monolayer-deep rectangular pits produced on an alkali halide surface by electron irradiation have been resolved at room temperature by non-contact atomic force microscopy. Molecules self-assemble in a specific fashion inside pits of width smaller than 15 nm. By contrast no ordered aggregates o...

Atomic stick-slip processes have been studied in detail by means of friction force microscopy with high spatial and temporal resolution. The influence of the tip-sample contact on the thermal fluctuations of the force sensor and on the dynamics of the stick-slip process are characterized. Results are compared with simulations based on an extended T...

So far, most of the high resolution scanning probe microscopy studies of organic molecules were restricted to metallic substrates. Insulating substrates are mandatory when the molecules need to be electrically decoupled in a electronic circuit. In such a case, atomic force microscopy is required. In this paper we will discuss our recent studies on...