Investigation of electron-induced cross-linking of self-assembled monolayers by scanning tunneling microscopy

Patrick Stohmann; Sascha Koch; Yang Yang; Christopher David Kaiser; Julian Ehrens; Jürgen Schnack; Niklas Biere; Dario Anselmetti; Armin Gölzhäuser; Xianghui Zhang

doi:10.3762/bjnano.13.39

Investigation of electron-induced cross-linking of self-assembled monolayers by scanning tunneling microscopy

Beilstein J Nanotechnol. 2022 May 25:13:462-471. doi: 10.3762/bjnano.13.39. eCollection 2022.

Authors

Affiliations

¹ Physics of Supramolecular Systems and Surfaces, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany.
² Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom.
³ Condensed Matter Theory Group, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany.
⁴ Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany.

Abstract

Ultrathin membranes with subnanometer pores enabling molecular size-selective separation were generated on surfaces via electron-induced cross-linking of self-assembled monolayers (SAMs). The evolution of p-terphenylthiol (TPT) SAMs on Au(111) surfaces into cross-linked monolayers was observed with a scanning tunneling microscope. As the irradiation dose was increased, the cross-linked regions continued to grow and a large number of subnanometer voids appeared. Their equivalent diameter is 0.5 ± 0.2 nm and the areal density is ≈1.7 × 10¹⁷ m^-2. Supported by classical molecular dynamics simulations, we propose that these voids may correspond to free volumes inside a cross-linked monolayer.

Keywords: carbon nanomembranes; electron-induced cross-linking; scanning tunneling microscopy; self-assembled monolayers; subnanometer pores.

Grants and funding

Financial support from the German Federal Ministry of Education and Research (BMBF) under the grants 03X0158A and 03XP0155A, as well as through the COST action CELINA (CM1301) is gratefully acknowledged. D.A. and N.B. acknowledge financial support from the German Research Foundation (DFG) under the contract AN 370/8-1. Y.Y. acknowledges funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 838593.