Search PubMed⌕ Search
Home/Archive/PubMed

PubMed · 14997266

Characterizing single crystal surfaces using high resolution electron diffraction.

D Thien·F-J Meyer zu Heringdorf·P Kury·M Horn-von Hoegen
View original source ↗Export metadata ↓

Abstract

Characterization and controlled manipulation of surfaces is a crucial factor in modern processing of the technologically relevant Si(100) surface. Using spot profile analyzing low energy electron diffraction, the morphological changes from a single stepped vicinal Si(100) surface to a single-domain (2x1) reconstructed surface have been investigated in situ during Si deposition. The temperature range for formation of this kinetically-stabilized single-domain surface was found to be 400-500 degrees C. This single-domain surface could be preserved for further characterization and experiments after quenching to room temperature.

Explore related subjects

CrystallizationMaterials TestingMicroscopy, Electron, TransmissionSiliconSurface PropertiesJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

D Thien, F-J Meyer zu Heringdorf, P Kury, M Horn-von Hoegen. 2004-03-03. Characterizing single crystal surfaces using high resolution electron diffraction.. https://doi.org/10.1007/s00216-004-2547-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2005

Homochiral oligopeptides generated by induced "mirror symmetry breaking" lattice-controlled polymerizations in racemic crystals of phenylalanine N-carboxyanhydride.

The formation of diastereoisomeric libraries of oligopeptides through the heterogeneous polymerization of racemic crystals of phenylalanine N-carboxyanhydride (PheNCA) is reported. The diastereoisomeric compositions of the oligopeptides formed on polymerization of (R,S) crystals incorporating the deuterium-tagged S enantiomer were determined by MALDI-TOF mass spectrometry. The racemic mixtures of the oligopeptides longer than pentamers are represented primarily by diastereoisomers of homochiral sequence and with peptides containing only one heterochiral repeating unit. A mechanism comprising the following three sequential steps to account for this unusual observation is proposed: 1) formation of dimers and trimers at a partially damaged liquid/solid interface, 2) chain propagation that takes place within the bulk of the crystal through a lattice-controlled "zipper-like" mechanism between homochiral molecules arranged in a head-to-tail motif to yield crystalline antiparallel beta-sheets of alternating oligopeptide chains of homochiral sequence of opposite handedness, and 3) enantiomeric cross-inhibition that results in chain termination. Induced desymmetrization of the racemic mixtures of the formed peptides was achieved by the polymerization of the mixed quasi-racemic crystals of (R)-PheNCA, ((S)-PheNCA), and (S)-ThieNCA (3-(2-thienyl)-alanine N-carboxyanhydride) of various compositions. These experiments resulted in the formation of nonracemic libraries of oligopeptides composed of homochiral chains of (R)-Phe and copolymers of randomly distributed (S)-Phe and (S)-Thie sequences. From these findings, we propose a stochastic model for the generation of libraries of nonracemic mixtures of oligopeptides from the polymerization of host (R,S)-PheNCA with racemic mixtures of other guest NCA amino acids dissolved in limited quantities in the crystal.

Crystallization↗