Extraterrestrial organic matter that fell on Earth 3.3 billion years ago

The meteorites bring it regularly, but it has left no trace of it. It has been identified and analyzed by researchers from the CNRS, Chimie ParisTech, the Universities of Tours and Lille. Their publication, in the journal Geochimica and Cosmochimica Acta, offers a first model to distinguish these molecules from elsewhere from those produced on Earth.

References of the article:

D. Gourier et al.
Extraterrestrial organic matter preserved in 3.33 Ga sediments from Barberton, South Africa.
Geochimica and Cosmochimica Acta - May 2019 - DOI: 10.1016 / j.gca.2019.05.009

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A new interpretation of neutron scattering spectra

The article presents a new interpretation of neutron scattering spectra by molecular systems that has much in common with the Franck-Condon theory describing the vibrational transitions in a molecule after absorption or emission of a photon. The principal elements are the quantum probabilities for the transitions between the energy levels of the studied system, which are induced by diffusion of a neutron. In this case, the fundamental concept of "energy landscapes", which was introduced by Hans Frauenfelder to describe the internal dynamics of proteins in terms of "jumps" between the minima of their (free) internal energy, can be integrated in the analysis of neutron scattering spectra by complex systems in general. The theory also provides an intuitive physical interpretation of Van Hove's correlation functions in the quantum regime, as well as their classical limit, which is usually considered in the analysis of quasi-elastic spectra of neutrons from proteins and other complex molecular systems.

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