2 research outputs found
Electronic Structure and Luminescence of Quasi-Freestanding MoS2 Nanopatches on Au(111)
Monolayers of transition metal dichalcogenides are interesting materials for
optoelectronic devices due to their direct electronic band gaps in the visible
spectral range. Here, we grow single layers of MoS2 on Au(111) and find that
nanometer-sized patches exhibit an electronic structure similar to their
freestanding analogue. We ascribe the electronic decoupling from the Au
substrate to the incorporation of vacancy islands underneath the intact MoS2
layer. Excitation of the patches by electrons from the tip of a scanning
tunneling microscope leads to luminescence of the MoS2 junction and reflects
the one-electron band structure of the quasi-freestanding layer
Visualizing the Role of Molecular Orbitals in Charge Transport through Individual Diarylethene Isomers
Diarylethene
molecules are prototype molecular switches with their
two isomeric forms exhibiting strikingly different conductance, while
maintaining similar length. We employed low-temperature scanning tunneling
microscopy (STM) to resolve the energy and the spatial extend of the
molecular orbitals of the open and closed isomers when lying on a
Au(111) surface. We find an intriguing difference in the extension
of the respective HOMOs and a peculiar energy splitting of the formerly
degenerate LUMO of the open isomer. We then lift the two isomers with
the tip of the STM and measure the current through the individual
molecules. By a simple analytical model of the transport, we show
that the previously determined orbital characteristics are essential
ingredients for the complete understanding of the transport properties.
We also succeeded in switching the suspended molecules by the current,
while switching the ones which are in direct contact to the surface
occurs nonlocally with the help of the electric field of the tip