Dissociative recombination of electrons with diatomic molecular cations above dissociation threshold: Application to H₂⁺ and HD⁺

Our approach to the dissociative recombination and competitive processes based on the multichannel quantum defect theory is extended to the full account of the dissociative excitation, including the electronic excitation of the molecular ion. Compared to other existing modelings, ours relies on a simpler and less-time-consuming discretization of the vibrational continua of the target ion and to a more accurate account of the Rydberg-valence interactions via a second-order solution of the Lippman-Schwinger equation. A thorough study of the competition among the dissociative recombination, vibrational excitation, and dissociative excitation is performed, including a detailed analysis of the two different mechanisms governing the ion dissociation. The application of our method to the high-energy electron collisions with H2+ and HD+ ions results in a cross section in good agreement with the best previous modeling and with the most recent measurements performed in the Test Storage Ring of the Max-Planck-Institut für Kernphysik in Heidelberg

Dissociative recombination and vibrational excitation of CO+: model calculations and comparison with experiment

The latest molecular data—potential energy curves and Rydberg/valence interactions—characterizing the super-excited electronic states of CO are reviewed, in order to provide inputs for the study of their fragmentation dynamics. Starting from this input, the main paths and mechanisms for CO+ dissociative recombination are analyzed; its cross sections are computed using a method based on multichannel quantum defect theory. Convoluted cross sections, giving both isotropic and anisotropic Maxwellian rate coefficients, are compared with merged-beam and storage-ring xperimental results. The calculated cross sections underestimate the measured ones by a factor of two, but display a very similar resonant shape. These facts confirm the quality of our approach for the dynamics, and call for more accurate and more extensive molecular structure calculations. Keywords: dissociative recombination, electron impact vibrational excitation, vibrationally excited, multichannel quantum defect theory (Some figures may appear in colour only in the online journal

Devastating Decline of Forest Elephants in Central Africa.

African forest elephants– taxonomically and functionally unique–are being poached at accelerating rates, but we lack range-wide information on the repercussions. Analysis of the largest survey dataset ever assembled for forest elephants (80 foot-surveys; covering 13,000 km; 91,600 person-days of fieldwork) revealed that population size declined by ca. 62% between 2002–2011, and the taxon lost 30% of its geographical range. The population is now less than 10% of its potential size, occupying less than 25% of its potential range. High human population density, hunting intensity, absence of law enforcement, poor governance, and proximity to expanding infrastructure are the strongest predictors of decline. To save the remaining African forest elephants, illegal poaching for ivory and encroachment into core elephant habitat must be stopped. In addition, the international demand for ivory, which fuels illegal trade, must be dramatically reduced