Electronically induced modification of thin layers on surfaces

Interactions of thermally and electronically stimulated reactions in thin layers on surfaces are investigated. For self-assembled monolayers, thermal activation promotes many processes primarily induced by electronic excitations. We demonstrate that the film temperature is an important parameter for steering these reactions towards different final products. Using chemisorbed water on Ru(001) as an example, we investigate how the products of an irradiation induced reaction catalyze thermally stimulated dissociation of water molecules

Exchange Reactions between Alkanethiolates and Alkaneselenols on Au{111}

When alkanethiolate self-assembled monolayers on Au{111} are exchanged with alkaneselenols from solution, replacement of thiolates by selenols is rapid and complete, and is well described by perimeter-dependent island growth kinetics. The monolayer structures change as selenolate coverage increases, from being epitaxial and consistent with the initial thiolate structure to being characteristic of selenolate monolayer structures. At room temperature and at positive sample bias in scanning tunneling microscopy, the selenolate-gold attachment is labile, and molecules exchange positions with neighboring thiolates. The scanning tunneling microscope probe can be used to induce these place-exchange reactions

A spectroscopic study of self-assembled monolayer of porphyrin-functionalized oligo(phenyleneethynylene)s on gold: the influence of the anchor moiety

Porphyrin-functionalized oligo(phenyleneethynylene)s (OPE) are promising molecules for molecular electronics applications. Three such molecules (1-3) with the common structure P-OPE-AG (P and AG are a porphyrin and anchor group, respectively) and different anchor groups, viz. an acetyl protected thiol, -S-COCH 3 (1), an acetyl protected thiol with methylene linker, -CH 2 -S-COCH 3 (2), and a trimethylsilylethynyl group, -C≡C-Si(CH 3 ) 3 (3) have been synthesized and the corresponding self-assembled monolayers (SAMs) on Au(111) substrates have been prepared. The integrity and structural properties of these films were studied by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The results suggest that the films formed from 1 have a high orientational order with an almost upright orientation and dense packing of the molecular constituents, i.e. represent a high quality SAM. In contrast, molecule 2 formed disordered molecular layers on Au, even though the molecule-surface bonding (thiolate) is the same as in the case of molecule 1. This suggests that the methylene linker in molecule 2 has a strong impact on the quality of the resulting film, so that a well-ordered SAM cannot be formed. The silane system, 3, is also able to bind to the gold surface but the resulting SAM has a poor quality, being significantly disordered and/or comprised of strongly inclined molecules. The above results suggest that the nature of the anchor group along with a possible linker is an important parameter which, to a high extent, predetermines the entire quality of OPE-based molecular layers

Reconnection methods for an arbitrary polyhedral computational grid

The paper suggests a method for local reconstructions of a 3D irregular computational grid and the algorithm of its program implementation. Two grid reconstruction operations are used as basic: paste of two cells having a common face and cut of a certain cell into two by a given plane. This paper presents criteria to use one or another operation, the criteria are analyzed. A program for local reconstruction of a 3D irregular grid is used to conduct two test computations and the computed results are given

Electronically induced modification of thin layers on surfaces

Interactions of thermally and electronically stimulated reactions in thin layers on surfaces are investigated. For self-assembled monolayers, thermal activation promotes many processes primarily induced by electronic excitations. We demonstrate that the film temperature is an important parameter for steering these reactions towards different final products. Using chemisorbed water on Ru(001) as an example, we investigate how the products of an irradiation induced reaction catalyze thermally stimulated dissociation of water molecules

The efficiency of using small-volume spraying in chemical protection of grapes from diseases in the conditions of Crimea

The article presents the results of studies carried out in 2020-2021 in soil and climatic conditions of the Mountain-Valley viticultural zone of Crimea to determine the efficiency of small-volume spraying in pest control of industrial vineyards of wine grape variety ‘Muscat Rose’. In experimental variant, when using small-volume spraying, the amount of working solution and the rate of pesticide application were reduced (operations on the concentration of working solution). It was established that against the background of protective measures of grape plantings in experimental and example (full-volume spraying) variants, a low level of oidium development was observed: up to 1.3% on leaves, 1.1% on bunches; and of black rot - up to 1.2% on bunches. At the same time, there was no significant difference in the intensity and dynamics of disease development in these variants. It was experimentally determined that in the experiment, when using small-volume (200-250 l/ha) and full-volume (example, 400-800 l/ha) sprayings, a good conditional yield of wine grapes ‘Muscat Rose’ was obtained - 2.5-2.6 kg/bush (52.4-54.7 c/ha). The use of full-volume and small-volume sprayings on experimental plots did not have a negative effect on the process of sugar accumulation (25.1-25.5 g/100 cm3) and the level of titratable acids (6.0-6.2 g/dm3) in grape yield. Thus, in the course of studies, it was found that using of small-volume spraying made it possible to increase the productivity of sprayers and reduce the pesticide load on ampelocenosis