Coordination mode of cyclohex-1-enylolonium cation and bridging pyridyl derivatives as gem-diol chelates to rhenium(I) and (VII)

Transition Metal Chemistry - Rhenium(I) and (VII) complexes with cyclohex-1-enylolonium cation and bridging pyridyl derivatives are reported. Additionally, the CO-bridged pyridyl and their related...     

UV and IR absorption cross-sections of HCHO, HCDO, and DCDO

UV (240-370 nm) and IR (3200-1500 cm(-1)) absorption cross-sections of HCHO, HCDO, and DCDO in a bath gas of N(2) at atmospheric pressure and 296 K are reported from simultaneous measurements in the two spectral regions. Cross-sections were placed on an absolute scale through quantitative conversion of formaldehyde to CO and HCOOH by titration with Br atoms, also monitored by FTIR. The integrated UV absorption cross-sections of HCHO, HCDO, and DCDO are equal to within the experimental uncertainty.     

Experimental intercomparison of the absorption cross-sections of nitrous acid (HONO) in the ultraviolet and mid-infrared spectral regions

Nitrous acid, HONO, is an important trace gas in tropospheric photochemistry, because it is a source of OH radicals. In order to obtain HONO concentrations from spectroscopic measurements, the knowledge of accurate absorption cross-sections is essential. Furthermore, the ultraviolet absorption cross-sections of HONO determine its atmospheric photolysis rates, which are still being debated. In particular, in a recent field study focusing on the photolysis frequency of HONO, the absolute values of the ultraviolet absorption cross-sections have been proposed as a potential source for systematic errors. For these reasons, we have compared the absorption cross-sections for HONO in the infrared (IR) and ultraviolet (UV) by performing simultaneous measurements in both spectral regions. Assuming that the IR cross-sections (that show good agreement between different studies) are correct, our study shows a good agreement between the consistent infrared studies and some selected accurate UV spectra published previously (about 6%) while a rather large disagreement (about 22%) is observed when using other UV data sets.     

A domain-specific embedded language in C++ for lowest-order discretizations of diffusive problems on general meshes

In this work we propose an original implementation of a large family of lowest-order methods for diffusive problems including standard and hybrid finite volume methods, mimetic finite difference-type schemes, and cell centered Galerkin methods. The key idea is to regard the method at hand as a (Petrov–)Galerkin scheme based on possibly incomplete, broken affine spaces defined from a gradient reconstruction and a point value. The resulting unified framework serves as a basis for the development of a FreeFEM-like domain specific language targeted at defining discrete linear and bilinear forms. Both the back-end and the front-end of the language are extensively discussed, and several examples of applications are provided. The overhead of the language is evaluated with respect to a more traditional implementation. A benchmark including the comparison with more classical finite element methods on standard meshes is also proposed.