TY - JOUR A1 - Koch, Sascha A1 - Kaiser, Christopher D. A1 - Penner, Paul A1 - Barclay, Michael A1 - Frommeyer, Lena A1 - Emmrich, Daniel A1 - Stohmann, Patrick A1 - Abu-Husein, Tarek A1 - Terfort, Andreas A1 - Fairbrother, D. Howard A1 - Ingólfsson, Oddur A1 - Gölzhäuser, Armin T1 - Amplified cross-linking efficiency of self-assembled monolayers through targeted dissociative electron attachment for the production of carbon nanomembranes JF - Beilstein Journal of Nanotechnology PY - 2017/// VL - 8 SP - 2562 EP - 2571 SN - 2190-4286 DO - 10.3762/bjnano.8.256 PB - Beilstein-Institut JA - Beilstein J. Nanotechnol. UR - https://doi.org/10.3762/bjnano.8.256 KW - 2D materials KW - carbon nanomembrane KW - dissociative electron attachment KW - dissociative ionization KW - helium ion microscopy KW - self-assembled monolayers KW - X-ray photoelectron spectroscopy N2 - The determination of the negative ion yield of 2′-chloro-1,1′-biphenyl (2-Cl-BP), 2′-bromo-1,1′-biphenyl (2-Br-BP) and 2′-iodo-1,1′-biphenyl (2-I-BP) upon dissociative electron attachment (DEA) at an electron energy of 0 eV revealed cross section values that were more than ten times higher for iodide loss from 2-I-BP than for the other halogenides from the respective biphenyls (BPs). Comparison with dissociative ionization mass spectra shows that the ratio of the efficiency of electron impact ionization induced fragmentation of 2-I-BP, 2-Br-BP, and 2-Cl-BP amounts to approximately 1:0.7:0.6. Inspired by these results, self-assembled monolayers (SAMs) of the respective biphenyl-4-thiols, 2-Cl-BPT, 2-Br-BPT, 2-I-BPT as well as BPT, were grown on a Au(111) substrate and exposed to 50 eV electrons. The effect of electron irradiation was investigated by X-ray photoelectron spectroscopy (XPS), to determine whether the high relative DEA cross section for iodide loss from 2-I-BPT as compared to 2-Br-BP and 2-Cl-BP is reflected in the cross-linking efficiency of SAMs made from these materials. Such sensitization could reduce the electron dose needed for the cross-linking process and may thus lead to a significantly faster conversion of the respective SAMs into carbon nanomembranes (CNMs) without the need for an increased current density. XPS data support the notation that DEA sensitization may be used to achieve more efficient electron-induced cross-linking of SAMs, revealing more than ten times faster cross-linking of 2-I-BPT SAMs compared to those made from the other halogenated biphenyls or from native BPT at the same current density. Furthermore, the transfer of a freestanding membrane onto a TEM grid and the subsequent investigation by helium ion microscopy (HIM) verified the existence of a mechanically stable CNM created from 2-I-BPT after exposure to an electron dose as low as 1.8 mC/cm2. In contrast, SAMs made from BPT, 2-Cl-BPT and 2-Br-BPT did not form stable CNMs after a significantly higher electron dose of 9 mC/cm2. ER -