Search

A brief review of the high spatial resolution Auger electron spectroscopy (HRAES) and its usage in metallurgy is presented. A combination of HRAES and X-ray photoelectron spectroscopy makes a powerful combination to resolve a large number of problems encountered in metallurgy. Several selected examples of such problems studied in the authors’ laboratory are presented: influence of surface active impurities on the surface properties and structure, chemical composition of nano-scaled inclusions, homogeneity of oxide layers formed by decarburization, chemical composition of inter- and intra-grain surfaces obtained by fracture in vacuum and interfacial study of 19Cr-13Ni austenitic stainless steel after treatment at elevated temperatures., Predočen je kratki pregled Auger-ove elektronske spektroskopije (HREAS) visoke spacijalne resolucije i njene primjene u metalurgiji. Kombinacija HREAS i röntgenske fotoelektronske spektroskopije učinkovita je pri rješavanju velikog broja problema koji se susreću u metalurgiji. Predočeno je nekoliko odabranih primjera takvih problema studiranih u laboratoriju autora: utjecaj površinski aktivnih nečistoća na svojstva i strukturu površine, kemijski sastav “nano-uključaka”, homogenost oksidnih slojeva nastalih odugljičenjem, kemijski sastav površina u zrnu i među zrnima nastalih lomljenjem u vakuumu te međufazna studija 19Cr-13Ni nehrđajućeg austenitnog čelika nakon obrade kod povišenih temperatura.

Edge-defined film-fed grown polycrystalline silicon sheets, grown with one face exposed to oxidizing CO gas added to the inert Ar atmosphere, were studied. Interaction of CO with molten silicon surface during growth produced SiC-like structures in a thin layer on the surface exposed to CO. Infrared spectroscopy results suggest that this layer is constituted of good quality SiC ; however, Raman and x-ray photoelectron spectroscopy showed that it consists of Si1− xCx in the form of small crystallites mixed with C- and O-rich silicon. Journal of Applied Physics is copyrighted by The American Institute of Physics.

The recently developed concept of topological resonance energy, TRE, (the optimal non-parametric realization of Dewars-type resonance energy, DRE) is applied to neutral (odd and even) and charged annulenes. Analytical expressions for TRE of neutral annulenes, their mono- and di-cations, and mono- and di-anions are derived. The results obtained are in good agreement with experimental findings for both neutral and charged annulenes.

A simple method based on a topological resonance energy index is proposed for predicting the reactivities of conjugated hydrocarbons. In comparison with other simple methods introduced (e.g., the Kekule structure count method') it embraces both alternant and non-alternant hydrocarbons without additional adjustment of the theory.

Mathematical relations necessary for the calculation of the previously introduced15 topological resonance energy, TRE, are derived. TRE, as defined in ref. 15, was rather inconvenient for numerical calculations. In the present work these computing difficulties are overcome. Acyclic characteristic polynomial pac and acyclic spectrum of a graph are defined and their close relationship to TRE is demonstrated. Hence, the evaluation of pac is the crucial .step in the computation of TRE's. A graphical procedure is described and exemplified for the determination of P"c's both for simple graphs and for graphs with loops and weighted edges.

Isomeric bicyclic conjugated systems consisting entirely of five-membered heterocycles were studied using a novel aromaticity index named topological resonance energy (TRE). TRE has correctly predicted the aromatic behaviour of all the groups of isomers studied. (These isomers called positional isomers because they formally differ only by the position of a-bivalent heteroatoms) may be classified into a particular group according their annelation mode, which closely parallels TRE predictions and experimental findings.

Annulenes were studied using the concept of aromatic stabilization. A simple expression is presented for the calculation of aromatic stabilization of annulenes. The index of aromatic stabilization differentiates correctly between the [4n + 2] - and [4n] -annulenes. The analysis of the approach of Kruszewski and Krygowski shows that their KK index differs only by a constant from the value of aromatic stabilization of a particular annulene. Similarly, the relation between REPE values of Hess and Schaad and indices of aromatic stabilization is discussed.