RING STRUCTURES ON NATURAL MOLYBDENUM-DISULFIDE INVESTIGATED BY SCANNING TUNNELING AND SCANNING FORCE MICROSCOPY

Ring-like structures of two different sizes on a nanometer scale have been found on natural molybdenum disulfide (MoS2). Investigation by scanning tunneling and scanning force microscopy as well as secondary-ion mass spectroscopy indicate that these rings might originate from included molecules. Synthetic compared to natural MoS2 shows characteristic differences. The origin of these striking structures could be the morphology of organic or even remnants of biological material included at the geological time when the mineral was formed and could therefore be regarded as a result of a molecular fossilization process. The alternative explanation that the ring structure is a nonmorphological and purely electronic effect caused by a point defect like a dopant is also discussed.