The roles of charged and neutral oxidising species in silicon oxidation from ab initio calculations

We examine the roles of charged oxidising species based on extensive ab initio density functional theory calculations. Six species are considered: interstitial atomic O, O-, O2- and molecular species: O-2, O-2(-), O-2(2-) We calculate their incorporation energies into bulk silicon dioxide, vertical electron affinities and diffusion barriers. In our calculations, we assume that the electrons responsible for the change of charge state come from the silicon conduction band, however, the generalisation to any other source of electrons is possible, and hence, our results are also relevant to electron-beam assisted oxidation and plasma oxidation. The calculations yield information about the relative stability of oxidising species, and the possible transformations between them and their charging patterns. We discuss the ability to exchange O atoms between the mobile species and the host lattice during diffusion, since this determines whether or not isotope exchange is expected. Our results show very clear trends: (1) the molecular species are energetically preferable over alo,nic ones, (2) the charged species are energetically more favourable than neutral ones, (3) diffusion of atomic species (O, O-, O2-) will result in oxygen exchange, whereas the diffusion of nzoleculai species (O-2, O-2(-), O-2(2-)) is not likely to lead to a significant exchange with the lattice. On the basis of our calculation, we predict that charging of oxidising species may play a key role in silicon oxidation process. (C) 2000 Elsevier Science Ltd. All rights reserved

Alexandroff duplicate and βκ

[EN] We discuss spaces and the Alexandroff duplicates of those spaces that admit a C-S embedding into the Cech-Stone compactification of a discrete space.Szymanski, AA. (2022). Alexandroff duplicate and βκ. Applied General Topology. 23(1):225-234. https://doi.org/10.4995/agt.2022.15586OJS22523423

Extinction Map of Baade's Window

Recently Wo\'zniak \& Stanek (1996) proposed a new method to investigate interstellar extinction, based on two band photometry, which uses red clump stars as a means to construct the reddening curve. I apply this method to the color-magnitude diagrams obtained by the Optical Gravitational Lensing Experiment (OGLE) to construct an extinction map of $(40')^2$ region of Baade's Window, with resolution of $\sim30\;arcsec$. Such a map should be useful for studies of this frequently observed region of the Galactic bulge. The map and software useful for its applications are available via {\tt anonymous ftp}. The total extinction $A_V$ varies from $1.26\;mag$ to $2.79\;mag$ within the $(40')^2$ field of view centered on $(\alpha_{2000}, \delta_{2000}) =$ (18:03:20.9,--30:02:06), i.e. $(l,b)=(1.001,-3.885)$. The ratio $A_V/E(V-I) = 2.49\pm0.02$ is determined with this new method.Comment: revised version accepted for publication in ApJ Letters, 8 pages, uuencoded PostScript with 4 figures included; complete paper available through WWW at http://www.astro.princeton.edu/~library/prep.html; tables and auxiliary software available at ftp://www.astro.princeton.edu/stanek/Extinctio

Projectively Solid Sets and an N-dimensional Piccard's Theorem

We discuss functions f : X × Y → Z such that sets of the form f (A × B) have non-empty interiors provided that A and B are non-empty sets of second category and have the Baire property