Zircon U-Pb Geochronology Links the End-Triassic Extinction with the Central Atlantic Magmatic Province

The end-Triassic extinction is characterized by major losses in both terrestrial and marine diversity, setting the stage for dinosaurs to dominate Earth for the next 136 million years. Despite the approximate coincidence between this extinction and flood basalt volcanism, existing geochronologic dates have insufficient resolution to confirm eruptive rates required to induce major climate perturbations. Here, we present new zircon uranium-lead (U-Pb) geochronologic constraints on the age and duration of flood basalt volcanism within the Central Atlantic Magmatic Province. This chronology demonstrates synchroneity between the earliest volcanism and extinction, tests and corroborates the existing astrochronologic time scale, and shows that the release of magma and associated atmospheric flux occurred in four pulses over about 600,000 years, indicating expansive volcanism even as the biologic recovery was under way

Thermal dependency of CO₂ VUV absorption cross section and application to warm exoplanetary atmospheres

International audienceMost of exoplanets detected so far have atmospheric temperatures significantly higher than 300 K. These exoplanets are often close to their star and thus receive an intense UV photons flux, triggering important pho-todissociation processes. However, the temperature dependency of VUV absorption cross sections, which are essential data to model photolyses in atmospheric models, are barely known. Thus, by lack of appropriate data, absorption cross sections at room temperature are used in photochemical models of extrasolar planets , leading to a non-measurable uncertainty. With the future space-or ground-based telescopes that will be developed in the coming years (JWST, E-ELT.. .) investigating these research fields becomes urgent [1]. In this context, we quantified the temperature dependency of the VUV absorption cross section of carbon dioxide (CO 2). We performed experimental measurements on the range (115-230 nm) between 150 and 800 K. The absorption cross section of CO 2 increases with the temperature (Fig. 1). At 200 nm, there are more than four orders of magnitude between the one at 300 K and the one at 800 K. We also determined a parametrisation to calculate the continuum of the absorption cross section on this wavelength range. We used these new data in our photo-thermochemical model for exoplanets [2] and studied the impact on the results (photolyses rates and chemical composition) as well as on the observables (synthetic transmission spectra) [3, 4]. We will present these experimental results and their consequences on the modelling of exo-planet atmospheres

Thermal dependency of CO₂ VUV absorption cross section and application to warm exoplanetary atmospheres

International audienceMost of exoplanets detected so far have atmospheric temperatures significantly higher than 300 K. These exoplanets are often close to their star and thus receive an intense UV photons flux, triggering important pho-todissociation processes. However, the temperature dependency of VUV absorption cross sections, which are essential data to model photolyses in atmospheric models, are barely known. Thus, by lack of appropriate data, absorption cross sections at room temperature are used in photochemical models of extrasolar planets , leading to a non-measurable uncertainty. With the future space-or ground-based telescopes that will be developed in the coming years (JWST, E-ELT.. .) investigating these research fields becomes urgent [1]. In this context, we quantified the temperature dependency of the VUV absorption cross section of carbon dioxide (CO 2). We performed experimental measurements on the range (115-230 nm) between 150 and 800 K. The absorption cross section of CO 2 increases with the temperature (Fig. 1). At 200 nm, there are more than four orders of magnitude between the one at 300 K and the one at 800 K. We also determined a parametrisation to calculate the continuum of the absorption cross section on this wavelength range. We used these new data in our photo-thermochemical model for exoplanets [2] and studied the impact on the results (photolyses rates and chemical composition) as well as on the observables (synthetic transmission spectra) [3, 4]. We will present these experimental results and their consequences on the modelling of exo-planet atmospheres

Imaging modes of atomic force microscopy for application in molecular and cell biology

Atomic force microscopy (AFM) is a powerful, multifunctional imaging platform that allows biological samples, from single molecules to living cells, to be visualized and manipulated. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM imaging in biology, various technological developments would be required to address certain limitations of the method. This has led to the creation of a range of new imaging modes, which continue to push the capabilities of the technique today. Here, we review the basic principles, advantages and limitations of the most common AFM bioimaging modes, including the popular contact and dynamic modes, as well as recently developed modes such as multiparametric, molecular recognition, multifrequency and high-speed imaging. For each of these modes, we discuss recent experiments that highlight their unique capabilities.Accepted Author ManuscriptBN/Andreas Engel La