Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Poster: Interfaces and Thin Films (joint session with DECHEMA and VDI)

CPP 9.30: Poster

Montag, 11. März 2013, 17:30–19:30, Poster C

Imaging chemically patterned self-assembled monolayers with helium-ion microscopy — •Daniel Emmrich, Henning Vieker, André Beyer, and Armin Gölzhäuser — Physics of Supramolecular Systems, University of Bielefeld, 33615 Bielefeld, Germany

Chemical patterning of certain self-assembled monolayers (SAMs) is possible by local exposure with electrons. In this way, for example, nitro groups of SAMs of NBPT (4'-nitro-1,1'-biphenyl-4-thiol) molecules convert into amino groups. This is accompanied by the formation of cross-links between molecules in the exposed monolayer. In this contribution the capability of helium-ion microscopy (HIM) for imaging chemical patterns in SAMs is discussed. To this end, SAMs of NBPT and BPT (1,1'-biphenyl-4-thiol) molecules are locally exposed by employing a stencil mask and an electron flood gun. HIM images of these samples at identical settings show a significant drop in the secondary-electron signal for the nitro-terminated areas in comparison to all other monolayer regions in this set of samples, i.e. the amino-terminated areas, the exposed as well as pristine SAMs from BPT molecules. This behaviour can be understood by considering the scattering of secondary electrons in the monolayer during the HIM imaging process. Imaging of fully cross-linked and chemically patterned SAMs as well as electron exposure dose sample series will be presented as well.