Using low-temperature scanning tunneling microscopy and occasionally synchrotron radiation methods we investigate molecules at surfaces. The experiments along with model calculations reveal molecular spin states and electron transport properties as well as intermolecular interactions. This talk will address phenomena such as spin-state switching in spin-crossover compounds. We further demonstrate that diamagnetic molecules can acquire a spin when they are arranged into suitable supramolecules on Pb. As a consequence, sharp resonances develop in the Pb superconductor gap. We harness them to enhance the inelastic tunneling spectroscopy of molecular vibrations. This new methods drastically increases the sensitivity and also improves the energy resolution beyond the thermal broadening limit.
Work done in collaboration with Alexander Weismann, Jan Homberg, Manuel Gruber, Troels Markussen, Sven Johannsen, Sascha Schüddekopf, Sascha Ossinger, Jan Grunwald, Alexander Herman, Heiko Wende, Felix Tuczek, Chao Li, Roberto Robles, Nicolas Lorente and Niklas Ide.