Electron‐Induced Hydration of an Alkene: Alternative Reaction Pathways

Rohdenburg

Beilstein J. Nanotechnol.

et al. 2018

Self Cite

Focused electron beam induced deposition (FEBID) is a versatile tool for the direct-write fabrication of nanostructures on surfaces. However, FEBID nanostructures are usually highly contaminated by carbon originating from the precursor used in the process. Recently, it was shown that platinum nanostructures produced by FEBID can be efficiently purified by electron irradiation in the presence of water. If such processes can be transferred to FEBID deposits produced from other carbon-containing precursors, a new general approach to the generation of pure metallic nanostructures could be implemented. Therefore this study aims to understand the chemical reactions that are fundamental to the water-assisted purification of platinum FEBID deposits generated from trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3). The experiments performed under ultrahigh vacuum conditions apply a combination of different desorption experiments coupled with mass spectrometry to analyse reaction products. Electron-stimulated desorption monitors species that leave the surface during electron exposure while post-irradiation thermal desorption spectrometry reveals products that evolve during subsequent thermal treatment. In addition, desorption of volatile products was also observed when a deposit produced by electron exposure was subsequently brought into contact with water. The results distinguish between contributions of thermal chemistry, direct chemistry between water and the deposit, and electron-induced reactions that all contribute to the purification process. We discuss reaction kinetics for the main volatile products CO and CH4 to obtain mechanistic information. The results provide novel insights into the chemistry that occurs during purification of FEBID nanostructures with implications also for the stability of the carbonaceous matrix of nanogranular FEBID materials under humid conditions.

Section: Resultsmentioning

confidence: 99%

“…Alcohols, on the other hand, can be formed through electron-initiated reactions. This was demonstrated for a condensed mixture of ethylene (C 2 H 4 ) and H 2 O [ 31 ]. Electron exposure initiated addition of H 2 O to the CC double bond of C 2 H 4 yielding ethanol (C 2 H 5 OH).…”

Section: Resultsmentioning

confidence: 99%

Electron-driven and thermal chemistry during water-assisted purification of platinum nanomaterials generated by electron beam induced deposition

Rohdenburg

Beilstein J. Nanotechnol.

et al. 2018

Self Cite

“…In consequence, the resonance remains accessible at electron energies that can be produced by simple non-monochromatized electron sources. This implies that such very low-energy resonances can in fact be exploited in the condensed phase to trigger selective reactions in electron-driven chemistry, a strategy proposed earlier using non-fluorinated formamide as an example [35] and pursued in recent work on the synthesis of ethanol from ethene and water driven by DEA [6].…”

Section: Discussionmentioning

confidence: 99%

“…a e-mail: kopyra@uph.edu.pl electrons [4][5][6], the condensed environment may also retain immediate products of the dissociative electronmolecule encounter. DEA reactions have so far been studied on many compounds and, in particular, on halogenated molecules because of their well-documented electron scavenging properties [1,7].…”

Section: Introductionmentioning

confidence: 99%

Low energy electron induced reactions in fluorinated acetamide – probing negative ions and neutral stable counterparts*

et al. 2016

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Abstract. Electron impact to trifluoroacetamide (CF3CONH2, TFAA) in the energy range 0-12 eV leads to a variety of negative fragment ions which are formed via dissociative electron attachment (DEA). The underlying reactions range from single bond cleavages to remarkably complex reactions that lead to loss of the neutral units HF, H2O and HNCO as deduced from their directly observed ionic counterparts (M -H2O) − , (M -HF) − and (M -HNCO) − . Also formed are the pseudo-halogen ions CN − and OCN − . All these reactions proceed dominantly via a resonance located near 1 eV, i.e., electrons at subexcitation energies trigger reactions involving multiple bond cleavages. The electron induced generation of the neutral molecules HF, H2O and HNCO in condensed TFAA films is probed by temperature controlled thermal desorption spectrometry (TDS) which can be viewed as a complementary techniques to gas-phase experiments in DEA to directly probe the neutral counterparts.

“…refs. [13][14][15][16]). UV photoelectron spectroscopy, quantum chemical and molecular dynamics calculations of BPT SAMs on gold, the formation of single-and double-links (carbon-carbon bonds) between phenyl rings of the molecules is expected during the crosslinking.…”

Section: Introduction: Materials Synthesis With Electron Beamsmentioning

confidence: 99%

Synthesis of Molecular 2D Materials via Low-energy Electron Induced Chemical Reactions

Turchanin

2019

Chimia

After the demonstration of a variety of inorganic two-dimensional (2D) materials (graphene, hBN, MoS 2 , etc.), molecular 2D materials have attracted a significant research interest as well. However, the direct synthesis of these materials is an exceptionally challenging task for chemists. In this review article, a simple and robust physical method for the synthesis of molecular 2D materials is presented based on low-energy electron induced chemical reactions in aromatic molecular layers. In this way, ultrathin (~1 nm) molecular nanosheets with adjustable chemical and physical properties called Carbon Nanomembranes (CNM) can be prepared. Moreover, the method enables the synthesis of various other 2D organic-inorganic hybrids (e.g. MoS 2 -CNM, graphene-CNM lateral heterostructures, etc.) or~20 nm thick nanosheets of organic semiconductors. Mechanisms of the reaction and functional properties of these molecular 2D materials including their chemical functionalization and engineering of hybrid hierarchical structures for application in nanoscience and nanotechnology are discussed in this article.