The comparison of exoplanets with well-studied Solar System planets can provide answers to the fundamental questions regarding their evolutionary path. The study of exoplanet atmospheres via high-resolution transmission spectroscopy has shown great success, especially for Jupiter-type planets. In the last years, this study also continued with promising investigations towards the atmospheric characterization of terrestrial exoplanets. 

One possible target for such investigation is the super Earth-sized exoplanet 55 Cnc e, which is one of the most studied terrestrial exoplanets to date. Currently, there are two possible atmospheric scenarios for 55 Cnc e: Either there is a heavy-weighted envelope with a significant amount of water or there is no gaseous envelope at all i.e. a rocky surface similar to Mercury, of our Solar System.

Here, we present high-resolution (R = 120 000) transit observation of this planet, acquired with the PEPSI instrument at the Large Binocular Telescope, aiming to search for absorption signatures from various species in the puzzling atmosphere of 55 CNC e.