138 research outputs found
Enantiosensitive Structure Determination by Photoelectron Scattering on Single Molecules
X-ray as well as electron diffraction are powerful tools for structure
determination of molecules. Electron diffraction methods yield
\r{A}ngstrom-resolution even when applied to large systems or systems involving
weak scatterers such as hydrogen atoms. For cases in which molecular crystals
cannot be obtained or the interaction-free molecular structure is to be
addressed, corresponding electron scattering approaches on gas-phase molecules
exist. Such studies on randomly oriented molecules, however, can only provide
information on interatomic distances, which is challenging to analyse in case
of overlapping distance parameters and they do not reveal the handedness of
chiral systems8. Here, we present a novel scheme to obtain information on the
structure, handedness and even detailed geometrical features of single
molecules in the gas phase. Using a loop-like analysis scheme employing input
from ab initio computations on the photoionization process, we are able to
deduce the three dimensional molecular structure with sensitivity to the
position individual atoms, as e.g. protons. To achieve this, we measure the
molecular frame diffraction pattern of core-shell photoelectrons in combination
with only two ionic fragments from a molecular Coulomb explosion. Our approach
is expected to be suitable for larger molecules, as well, since typical size
limitations regarding the structure determination by pure Coulomb explosion
imaging are overcome by measuring in addition the photoelectron in coincidence
with the ions. As the photoelectron interference pattern captures the molecular
structure at the instant of ionization, we anticipate our approach to allow for
tracking changes in the molecular structure on a femtosecond time scale by
applying a pump-probe scheme in the future
Edge Detection by Adaptive Splitting II. The Three-Dimensional Case
In Llanas and Lantarón, J. Sci. Comput. 46, 485–518 (2011) we proposed an algorithm (EDAS-d) to approximate the jump discontinuity set of functions defined on subsets of ℝ d . This procedure is based on adaptive splitting of the domain of the function guided by the value of an average integral. The above study was limited to the 1D and 2D versions of the algorithm. In this paper we address the three-dimensional problem. We prove an integral inequality (in the case d=3) which constitutes the basis of EDAS-3. We have performed detailed computational experiments demonstrating effective edge detection in 3D function models with different interface topologies. EDAS-1 and EDAS-2 appealing properties are extensible to the 3D cas
Metamizole versus ibuprofen at home after day surgery: study protocol for a randomised controlled trial
The evaluation and application of multilocus variable number tandem repeat analysis (MLVA) for the molecular epidemiological study of Salmonella enterica subsp. enterica serovar Enteritidis infection
Area deprivation and the prevalence of type 2 diabetes and obesity: analysis at the municipality level in Germany
Climate change impacts on stand structure and competitive interactions in a southern Swedish spruce–beech forest
Syntheses with nitrile oxides. 2. Reaction of aromatic nitrile oxides with bis(trimethylsilylcarbodiimide)
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