Chemical Principles and Interference in the Electrical Conductance of Single Molecules

Anders Christian Borges

Abstract

The electrical conductance of single molecules are routinely reported in the scientific
literature and off-resonant coherent tunneling is believed to be the mechanism
for transport in some of these experiments. In these experiments it is observed that,
in spite of similar molecular structures, the conductance of molecules can vary orders
of magnitude and the concept of interference is believed to play a major role
in this. This thesis investigates the links between single molecule conductance,
chemistry and interference effects in short organic molecules. It is investigated to
which extent the conductance can be understood in terms of separate contributions
and when the effects of interference are important. Links between chemical principles
and constructive- and destructive interference effects are demonstrated using a
combination of simple models, atomistic calculations and Scanning-Tunneling Microscope
Break-Junction experiments (STM-BJ). It is demonstrated that these links
can be used to design molecules exhibiting surprising interference effects and to interpret
and predict the trends in the characteristic conductance of single molecules
without resorting to numerical computational methods
OriginalsprogEngelsk
ForlagDepartment of Chemistry, Faculty of Science, University of Copenhagen
Antal sider175
StatusUdgivet - 2017

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