The effect of electron irradiation on aromatic thiolate selfassembled monolayers (SAMs) with oligophenyl, acene, and oligo(phenylene ethynylene) (OPE) backbones, containing from one to three phenyl rings, was studied, with emphasis on the basic irradiation-induced processes and performance of these films as negative resists in electron lithography. All films exhibited similar behavior upon the irradiation, with clear dominance of crosslinking, taking hold of the systems at already very early stages of the treatment. The cross sections for the modification of the SAM matrix and the damage of the SAM−substrate interface were determined for the primary electron energy of 50 eV, frequently used for the fabrication of carbon nanomembranes (CNM). They show only slight dependence on the backbone character as demonstrated by the example of the three-ring films. The two-ring systems exhibited the best performance as lithographic resists, with an optimal dose of 10−20 mC/cm 2 at 0.5−1 keV. The performance of the onering and three-ring systems was limited by a poor ability to form an extensive cross-linking network and by high resistance of the pristine films to the etching agents, respectively. Another process, associated with the poor lithographic performance of the threering systems but occurring at high doses for the two-ring systems as well, was a spontaneous release of the cross-linked films within the irradiated areas, in form of CNM pieces. From the lithographic data, cross sections of the irradiation-induced crosslinking were derived and discussed in context of backscattering and secondary electron yield. For the three-ring systems, fabrication of CNMs was demonstrated, for the first time in the OPE case.

We present a method for a bottom-up synthesis of atomically thin graphene sheets with tunable crystallinity and porosity using aromatic self-assembled monolayers (SAMs) as molecular precursors. To this end, we employ SAMs with pyridine and pyrrole constituents on polycrystalline copper foils and convert them initially into molecular nanosheetscarbon nanomembranes (CNMs)via low-energy electron irradiation induced cross-linking and then into graphene monolayers via pyrolysis. As the nitrogen atoms are leaving the nanosheets during pyrolysis, nanopores are generated in the formed single-layer graphene. We elucidate the structural changes upon the cross-linking and pyrolysis down to the atomic scale by complementary spectroscopy and microscopy techniques including X-ray photoelectron and Raman spectroscopy, low energy electron diffraction, atomic force, helium ion, and high-resolution transmission electron microscopy, and electrical transport measurements. We demonstrate that the crystallinity and porosity of the formed graphene can be adjusted via the choice of molecular precursors and pyrolysis temperature, and we present a kinetic growth model quantitatively describing the conversion of molecular CNMs into graphene. The synthesized nanoporous graphene monolayers resemble a percolated network of graphene nanoribbons with a high charge carrier mobility (∼600 cm2/(V s)), making them attractive for implementations in electronic field-effect devices.

On the basis of the observation that the formation of a strong bond results in the alternating weakening and strengthening of consecutive bonds, a concept of controlled bond strength modulation for protective groups in surface chemistry is suggested. The viability of this concept is demonstrated by the example of technologically relevant selenolate monolayers on Au(111): an Se–C bond to the protective benzyl group in air-stable organo­(benzyl)­selanes, serving as the monolayer precursors, is synergistically weakened upon contact of the selenium atom with gold (strong interaction) resulting in the cleavage of this bond and loss of the protective benzyl group. The extent of the bond weakening, which has been demonstrated for both aliphatic and aromatic systems, could be adjusted by the electron density at the benzyl group.

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Novel azobenzene-substituted self-assembled monolayers were used for stimuli-responsive work function variation, with control of the molecular dipole and sterical constraints.