Characterization of the Magnetism and Conformation of Single Porphyrin Molecules Adsorbed on Surfaces, and Artificial Graphene Nanoflakes

My thesis mostly focusses on the systems of porphyrin molecules adsorbed on single-crystalline metallic surfaces. Cyclic tetrapyrrole porphyrins play key roles in many important chemical and biological processes, such as oxygen transport in heme (iron porphyrin), electron transfer and oxidation reactions in photosynthetic chlorophyll (magnesium porphyrin). Comprehensive understanding of the magnetic and conformational properties of single porphyrin molecules adsorbed on metallic substrates attracts intensive research interest. In my thesis, I have studied the structural and electronics properties of porphyrin molecules by Low-temperature scanning tunneling spectroscopy (LT-STM) and scanning tunneling spectroscopy (STS) and theoretical methods. Owing to the high resolution of LT-STM, both geometric and electronic properties at the atomic level were probed. Moreover, the experimental results were understood by comprehensive theoretical methods, i.e. density functional theory, molecular dynamics, tight-binding and plane-wave expansion calculations.