It's hard to imagine that we can take a splinter and sharpen it down to the atomic level. It's even more impressive that we can bring this sharp tip close to a surface, scan it over the surface, and be sensitive to the tiny forces between the apex atom and individual atoms on the surface. Measuring and interpreting these forces is the goal of high-resolution atomic force microscopy (AFM). We perform frequency-modulation AFM (FM-AFM), in which we oscillate the tip and record the change in frequency as a measure of the interaction with the surface. FM-AFM performed in vacuum with stiff sensors has lead to amazing discoveries. Now, we are returning to the challenge of imaging samples in device- and biologically-relevant conditions. This contribution summarizes work that was performed in the Giessibl group to image with atomic resolution in ambient and liquid environments. We demonstrated atomic resolution with the qPlus sensor on KBr, and followed this with investigations on graphitic surfaces. We have also shown single-atomic defects and steps on the calcite surface. [DOI: 10.1380/ejssnt.2018.351]

This paper modestly expands an invited talk at ISSS-8 with the same title. After reviewing the relevant interactions between adsorbates on substrates with metallic surface states [especially Cu(111)], it focuses on organic adsorbates. Of particular interest are those which form honeycomb lattices with pores of various sizes. The nature of the confined states derived from the surface-state electrons is discussed as their effect on admolecules inside the pores. [DOI: 10.1380/ejssnt.2018.201]

The electron spin governs many phenomena in modern condensed matter physics, such as magnetism, superconductivity, etc. Often, minute details in the electronic structure determine the physical behavior of a material. Photoelectron emission—being the most established approach to explore electronic structures—is currently entering a new era thanks to a breathtaking development in light sources, spectrometer concepts, and spin detectors. In particular, the evolution in novel highly efficient electron spin polarimeters opens up new experimental opportunities and permits unequaled insights into the electronic structure. This contribution will discuss several examples in this field of spin-dependent interactions and spin-based phenomena. A prominent one refers to the class of topological insulators, where strong spin-orbit coupling (SOC) causes a unique spin-momentum locking around the Dirac cone. Transition metal dichalcogenides consist of quasi-2D layers coupled by v. d. Waals interactions. Here, strong SOC leads to pronounced hybridization effects. We also address fundamental issues in ferromagnetism, e.g., the complex interplay of SOC and exchange interaction, causing characteristic k-, spin- and symmetry-dependent band mixing. Using spin- and time-resolved photoemission we explore ultrafast spin dynamics in ferromagnets driven by strong ultrashort laser pulses. We find the changes in both majority and minority spin states to take place on a 100 fs time scale and to be compatible with band mirroring.
In this contribution, we will discuss several new aspects of spin-dependent and spin-resolved photoemission covering both static and dynamic issues of electronic states. [DOI: 10.1380/ejssnt.2018.177]