The structure and formation of hydrogen-bonded molecular networks on Au(111) surfaces revealed by scanning tunnelling and torsional-tapping atomic force microscopy

摘要

In a recent paper~1 on the bimolecular network consisting of 1,3,5-triazine-2,4,6-triamine (melamine) and perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) an apparent paradox in imaging of the molecular components was reported between networks prepared and imaged in ultrahigh vacuum (UHV) environment and networks prepared from solution and imaged under ambient conditions. The failure to image melamine as part of the network with ambient scanning tunneling microscopy (STM) was suggested to arise from an electronic effect. The paper also reports formation of multilayers before completion of the network monolayer and, thus, questions the suitability of the current strategy for preparing extended monolayers of the PTCDI-melamine network. As shown below these results are not intrinsic properties of the system. Both points are related and a result of the particular choice of preparation parameters.