Fingerprints for Structural Defects in Poly(thienylene vinylene) (PTV): A Joint Theoretical–Experimental NMR Study on Model Molecules

In the field of plastic electronics, low band gap conjugated polymers like poly(thienylene vinylene) (PTV) and its derivatives are a promising class of materials that can be obtained with high molecular weight via the so-called dithiocarbamate precursor route. We have performed a joint experimental- theoretical study of the full NMR chemical shift assignment in a series of thiophene-based model compounds, which aims at (i) benchmarking the quantum-chemical calculations against experiments, (ii) identifying the signature of possible structural defects that can appear during the polymerization of PTV's, namely head-to-head and tail-to-tail defects, and (iii) defining a criterion regarding regioregularity

Assessment of the Earth’s Cold Plasmatrough Modeling by Using Van Allen Probes/EMFISIS and Arase/PWE Electron Density Data

The Space Weather Integrated Forecasting Framework (SWIFF) Plasmasphere Model (SPM) is a 3D kinetic model of the plasmasphere coupled to the ionosphere. This combined system has been routinely used to evaluate principally the plasmapause formation and evolution, and the plasmasphere’s dynamics. The model contains analytical equations for the plasmasphere and plasmatrough regions that have been empirically determined using observations of satellite and ground-based data. In the present work, a revision of the plasmatrough equations is proposed using electron density data from the Van Allen Probes mission and paying particular attention to the spatiotemporal variation as well as to geomagnetic activity influence. Comparisons are performed with other parametrizations and with electron density data from the Arase mission. This assessment demonstrates that the plasmatrough electron density was slightly underestimated with respect to the new observations, in particular for high L values (L > 3) and high geomagnetic activity. In addition, the overall performance of the new parametrization follows a satisfactory general trend despite a large variability of density data observed in the plasmatrough. The plasmatrough is separated from the refilling zone in the model by considering vestigial and outer edge plasmapause positions

Electron dropout events and flux enhancements associated with geomagnetic storms observed by PROBA‐V/Energetic particle telescope from 2013 to 2019

Electron flux variations for E > 500 keV during geomagnetic storms are investigated using the Energetic Particle Telescope (EPT). This detector launched in May 2013 on board the satellite PROBA-V at an altitude of 820 km was designed to provide uncontaminated spectra of electrons, protons, and alpha particles. Electron flux dropout events are observed during the main phase of each storm and even during substorms: a rapid reduction of the electron flux is noted throughout the outer electron radiation belt at all energies above about 0.5 MeV on timescales of a few hours. The electron spectrograms measured by the EPT between 2013 and 2019 show that after each geomagnetic storm, dropout events are followed by a flux enhancement starting first at low L values, and reaching the slot or even the inner belt for the strongest storms. We determine the link between Disturbed Storm Time (Dst) and the minimum value of the L-shell where the dropouts deplete the outer belt, as well as the nonlinear relation between Dst and the minimum L-shell where the flux penetrates in the slot region or even the inner belt during the storms. Dropouts appear at all energies measured by EPT and penetrate down to L∼3.5 for the strongest events. Dropouts are observed at Low Earth Orbit each time Dst has an inverted peak 1 MeV, this limit is also linked to the plasmapause position