Adjustment of the Work Function of Pyridine and Pyrimidine Substituted Aromatic Self-Assembled Monolayers by Electron Irradiation

Sauter, Eric; Yildirim, Can; Terfort, Andreas; Zharnikov, Michael

doi:10.1021/acs.jpcc.7b03302

Cited by 18 publications

(32 citation statements)

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“…Depending on the chemical and structural composition of the monolayer, the interaction of electron beams with SAMs can be used to initiate different processes that include partial desorption, − cross-linking of aromatic molecules, − and surface modification of their chemical functionality . As demonstrated in recent years, these fundamental processes in turn can be used for different types of lithography of organic − and inorganic , materials, the formation of chemical gradients on the surface, metal substrate work function modification, and transforming SAMs into carbon-based materials such as graphene , or carbon nanomembranes (CNMs). − …”

Section: Introductionmentioning

confidence: 99%

Odd–Even Effect in Electron Beam Irradiation of Hybrid Aromatic–Aliphatic Self-Assembled Monolayers of Fatty Acid

et al. 2021

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Electron irradiation of aromatic self-assembled monolayers (SAMs) in combination with different lithographic approaches provides an interesting alternative for high-resolution surface patterning. More recently, it has been also demonstrated that this process can be used for carbon nanomembrane (CNM) fabrication, which forms technologically attractive 2D materials, with potential applications in different areas of nanotechnology such as ultrafiltration and nanobiosensing. To better understand the relation between the original SAM structure and the resulting CNM formation, in the current study, we conduct systematic analysis of the electron irradiation process for a model SAM system deposited on Ag substrates and based on a homologue series of biphenyl substituted carboxylic acids [C 6 H 5 −C 6 H 4 −(CH 2 ) n −COO/Ag, n = 2−6] with different lengths of the aliphatic linker defined by the number n. Our results of X-ray photoelectron spectroscopy of irradiated monolayers show that the process of electron-induced desorption, cross-linking, and elimination of the SAM binding group depend on the parity of the parameter n (the odd−even effect). Our observations indicate a way for controlling thickness and purity of such nanomembranes, which are the key parameters determining the range of CNM applications.

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Section: Introductionmentioning

confidence: 99%

Odd–Even Effect in Electron Beam Irradiation of Hybrid Aromatic–Aliphatic Self-Assembled Monolayers of Fatty Acid

et al. 2021

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“…lasers, ultraviolet light, X-rays) or particles' beams (electrons, ions). [11][12][13][14][15][16] Interestingly, the resolution of these lithographs is determined by the size of the beam applied to the SAM, 3 being the implementation cost and the needing of the precise control of the damaging 17 process the main factors that represent potential disadvantages. For this reason, the study of radiation damage (by electrons or X-rays) in SAMs are important to improve lithographic processes.…”

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confidence: 99%

Mechanistic Framework for the Formation of Different Sulfur Species by Electron Irradiation of n-Dodecanethiol Self-Assembled Monolayers on Au(111) and Au(100)

et al. 2020

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The electron induced damage in self-assembled monolayers (SAMs) of n-dodecanethiolate on Au(111) and Au(100) single-crystalline surfaces is investigated in situ by X-ray photoelectron spectroscopy. The same irradiation dose produced different adsorbed groups. The damage at the headgroup-substrate interface leads to find dialkyl sulfide (RS-R') on Au(111), while dialkyl disulfide (RS-SR) and/or thiol (RSH) were produced on Au(100). With regards to C species, significant amounts of C=C are generated on Au(111) but not on Au(100), showing that the double bond formation is not triggered through the same pathways on these surfaces. A detailed analysis of a variety of mechanisms, which involved cationic (RS + ), anionic (RS − ) or thiyl radical (RS • ) species, in combination with ab-initio DFT calculation leads to the conclusion that the radical pathways successfully explain the experimental results. Molecular dynamics simulations show that the n-dodecanethiolate-SAMs on both surfaces are equivalent with regard to the van der Waals interactions. The breakage of the S-Au bonds is studied by means of DFT calculations. The thiyl radical would form close to the Au(100) surface, making it likely to react with another thiyl radical or thiolate to form the RS-SR species. On the other hand, for Au(111) the thiyl radical would form farther from the surface, reacting with the alkyl chains of neighboring molecules to form RS-R' species. The mechanistic framework here proposed is very useful to explain the behavior of related systems.

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“…16,17 In general, apart from pure scientific and e-beam/X-ray damage aspects, [18][19][20] electron irradiation of SAMs represents an important physical tool for the functionalization and patterning of surfaces. It was, in particular, used for creation of sophisticated mixed SAMs, 21,22 fabrication of chemical gradients, 23,24 fixation of metal films at the SAM-ambient interface, 25,26 work function tuning, 27 SAM-based lithography and related nanofabrication, 24,[28][29][30][31][32][33][34][35][36][37][38][39][40] and preparation of SAM-based carbon nanomembranes (CNMs). [41][42][43][44][45][46][47] Such nanomembranes can, in general, be prepared from aromatic SAMs by relying on electron-induced cross-linking of the molecular backbones.…”

Section: Introductionmentioning

confidence: 99%

Electron-Induced Modification of Self-Assembled Monolayers of Aromatic Carboxylic Acids

et al. 2020

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The effects of low energy electrons on aromatic self-assembled monolayers (SAMs) with carboxylic acid (CA) docking groups were studied with focus on the dose range below 5 mC/cm 2 . The SAMs were prepared on underpotentially deposited Ag bilayer and comprised non-substituted and CA-substituted monolayers with the rod-like biphenyl backbone and a monolayer of a Y-shaped, CA-substituted molecule, 1,3,5-benzenetribenzoic acid (H3BTB), formed either as a single-component film or as a binary one by mixing with adamantane-CA (Ad-CA). X-ray photoelectron and near-edge X-ray absorption fine structure spectra suggest a high proneness of the CA groups at both the SAM/substrate and SAM/ambient interface to electron irradiation. Cleavage of the carboxylate-substrate bond results in a substantial molecular desorption at the initial stage of irradiation until electron-induced cross-linking gradually takes over. The CA groups at the outer SAM interface undergo substantial chemical changes indicating that they participate in the cross-linking chemistry. The electron-induced processes are accompanied by molecular reorientation. Disordering concluded for the SAMs formed by the rod-like molecules is contrasted by the H3BTB based systems where changes also occur but some molecular order is preserved as explained by a proposed model invoking conformational changes. In SAMs of H3BTB mixed with Ad-CA the latter shows a higher proneness to irradiation-induced desorption than the former as well as an influence on the cross-linking chemistry. The results of the present study suggest that CA-based SAMs on Ag offer additional options for cross-linking in SAMs and, as exemplarily demonstrated by the generation of Cu patterns on structured H3BTB templates, can be efficiently used for lithography and nanofabrication.

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Adjustment of the Work Function of Pyridine and Pyrimidine Substituted Aromatic Self-Assembled Monolayers by Electron Irradiation

Cited by 18 publications

References 50 publications

Odd–Even Effect in Electron Beam Irradiation of Hybrid Aromatic–Aliphatic Self-Assembled Monolayers of Fatty Acid

Odd–Even Effect in Electron Beam Irradiation of Hybrid Aromatic–Aliphatic Self-Assembled Monolayers of Fatty Acid

Mechanistic Framework for the Formation of Different Sulfur Species by Electron Irradiation of n-Dodecanethiol Self-Assembled Monolayers on Au(111) and Au(100)

Electron-Induced Modification of Self-Assembled Monolayers of Aromatic Carboxylic Acids

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