Modification of biphenylselenolate monolayers by low‐energy electrons

Weidner, Tobias; Ballav, Nirmalya; Grunze, M.; Terfort, Andreas; Zharnikov, Michael

doi:10.1002/pssb.200945078

Cited by 20 publications

(25 citation statements)

References 75 publications

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“…Such a difference confirms the much higher efficiency of the cross-linking process in the case of BP n COO/Ag systems which effectively quenches desorption and thus thickness reduction upon electron irradiation. The same mechanism was also reported earlier for purely aromatic SAMs based on biphenyl thiols and selenols where even lower values of cross-section for thickness reduction were reported (∼2 × 10 –17 cm 2 ) . In fact, we expect that the efficiency of the cross-linking process for BP n COO/Ag compared to that for alkanethiols must be even higher considering very efficient elimination of the anchoring group in the case of BP n COO/Ag ( vide infra ) with at the same time very little efficiency of this process for SAMs based on thiols on the Ag or Au , substrate.…”

Section: Resultssupporting

confidence: 79%

“…The same mechanism was also reported earlier for purely aromatic SAMs based on biphenyl thiols and selenols where even lower values of cross-section for thickness reduction were reported (∼2 × 10 −17 cm 2 ). 54 In fact, we expect that the efficiency of the cross-linking process for BPnCOO/Ag compared to that for alkanethiols must be even higher considering very efficient elimination of the anchoring group in the case of BPnCOO/Ag (vide inf ra) with at the same time very little efficiency of this process for SAMs based on thiols on the Ag 25 or Au 8,55 substrate. As shown in Figure 1a, together with the intensity, the position, that is, the BE of the main component of C 1s, is modified upon electron irradiation.…”

Section: Resultsmentioning

confidence: 99%

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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: Resultssupporting

confidence: 79%

Section: Resultsmentioning

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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“…For the former three SAMs, the thickness decreases by 25–30% at a dose of 4 mC/cm 2 . Such a relatively large reduction in thickness, which is significantly larger than that of thiol SAMs (≤ 10%) , and also reported for BP2-CA (∼28%), is related to the irradiation-induced processes at the SAM–substrate interface and points to the desorption of entire molecules before cross-linking in the SAM takes over. We note at this point that film thickness reflects the amount of material present.…”

Section: Resultssupporting

confidence: 56%

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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“…The relative increase of intensity of the 135 meV loss can be understood as resulting from increasing stretching contributions ascribed to simple C-C bonds. 56,61,62 Cross-linking was reported for aromatic SAMs under electron irradiation at 10 eV, 24,63 50 eV 8,25,27,28,30,64,65 and higher energies. 29,66 The mechanisms proposed involve primary and secondary electrons that are emitted from the SAM-substrate system, 67 which cause C-H bond breaking within the film.…”

Section: Resultsmentioning

confidence: 96%

Low-energy electron induced resonant loss of aromaticity: consequences on cross-linking in terphenylthiol SAMs

Amiaud

Houplin

Bourdier

et al. 2014

Phys. Chem. Chem. Phys.

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Aromatic self-assembled monolayers (SAMs) can be used as negative tone electron resists in functional surface lithographic fabrication. A dense and resistant molecular network is obtained under electron irradiation through the formation of a cross-linked network. The elementary processes and possible mechanisms involved were investigated through the response of a model aromatic SAM, p-terphenylthiol SAM, to low-energy electron (0-10 eV) irradiation. Energy loss spectra as well as vibrational excitation functions were measured using High Resolution Electron Energy Loss Spectroscopy (HREELS). A resonant electron attachment process was identified around 6 eV through associated enhanced excitation probability of the CH stretching modes ν(CH)(ph) at 378 meV. Electron irradiation at 6 eV was observed to induce a peak around 367 meV in the energy loss spectra, attributed to the formation of sp(3)-hybridized CHx groups within the SAM. This partial loss of aromaticity is interpreted to be the result of resonance formation, which relaxes by reorganization and/or CH bond dissociation mechanisms followed by radical chain reactions. These processes may also account for cross-linking induced by electron irradiation of aromatic SAMs in general.

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Modification of biphenylselenolate monolayers by low‐energy electrons

Cited by 20 publications

References 75 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

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

Low-energy electron induced resonant loss of aromaticity: consequences on cross-linking in terphenylthiol SAMs

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