% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Weiss:16436,
      author       = {Weiss, Christian},
      title        = {{STM} beyond vacuum tunnelling, a route to ultra high
                      resolution},
      volume       = {47},
      type         = {Dr. (FH)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-16436},
      isbn         = {978-3-89336-813-6},
      series       = {Schriften des Forschungszentrums Jülich.
                      Schlüsseltechnologien / Key Technologies},
      year         = {2011},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Direct imaging is a fast and reliable method for the
                      characterization of surfaces. When it comes to small surface
                      structures in the size of the features e.g. in todays
                      computer processors, classical optical imaging methods fail
                      in resolving these structures. With the invention of the
                      scanning tunnelling microscope (STM) for the first time it
                      became possible to image the structure of surfaces with
                      atomic precision. However, the STM fails in resolving
                      complex chemical structures like e.g. organic molecules. The
                      lack of chemical sensitivity in STM images can be overcome
                      by the condensation of molecular hydrogen or deuterium in
                      the STM junction. Images recorded in the so-called scanning
                      tunnelling hydrogen microscopy (STHM) closely resemble the
                      chemical structure of different organic molecules. However,
                      the mechanism behind the contrast formation has not been
                      addressed so far. Here we show that the origin of the STHM
                      contrast is a single hydrogen (H$_{2}$) or deuterium
                      (D$_{2}$) molecule located directly below the tip apex that
                      acts as a combined sensor and signal transducer. Together
                      with the tip the gas molecule forms a nano-scale force
                      sensor, comparable to sensors in atomic force microscopy
                      (AFM), which probes the total electron density (TED) of the
                      surface trough the Pauli repulsion and converts this signal
                      into variations of the junctions’ conductance again via
                      Pauli repulsion. Other than the sensors in conventional
                      scanning force techniques, due to its size, the sensor of
                      the STHM junction is intrinsically insensitive to long-range
                      forces, usually limiting the image resolution. The
                      insensitivity to long-range forces results in a high image
                      resolution, so that even small changes in the TED leave a
                      mark in obtained STHM images. The resolution hereby reaches
                      an unprecedented level as can be seen by the direct imaging
                      of local intermolecular interactions like e.g. hydrogen
                      bonds appear with remarkable clarity in STHM images of
                      organic layers. Thus, besides the identification of chemical
                      species of different adsorbates, the STHM mode allows the
                      study of interactions between adsorbates which e.g. lead to
                      their self organization on the surface. Therefore, the STHM
                      mode may give important insight in the driving mechanisms
                      behind the formation and composition of matter on the atomic
                      level. However, the STHM mode, in which a single H$_{2}$
                      (D$_{2}$) molecule probes the TED of the surface, is only
                      one example of a broader class of sensors. It is
                      conceivable, that by an appropriate choice of the molecule
                      in the junction, other surface properties can be imaged
                      which are usually inaccessible by other imaging techniques.},
      cin          = {PGI-3 / JARA-FIT},
      cid          = {I:(DE-Juel1)PGI-3-20110106 / $I:(DE-82)080009_20140620$},
      pnm          = {Grundlagen für zukünftige Informationstechnologien},
      pid          = {G:(DE-Juel1)FUEK412},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/16436},
}