Tuning the electronic, photophysical and charge transfer properties of small D-A molecules based on Thienopyrazine-terthienyls by changing the donor fragment: A DFT study

Indexación: Scopus.Four acceptor-donor organic conjugated molecules based on thieno[3,4-b]pyrazine-terthienyls were analyzed in order to explore the effect of the donor substituent on their molecular structures, electronic and optical properties. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD/DFT) calculations were carried out employing the B3LYP hybrid functional in combination with the 6-31G(d,p) basis set. The results suggests that the addition of electron-donating substituents to the conjugated molecules can diminish their energy gap value, which is beneficial to the photon harvesting. The lowest-lying absorption spectra of compounds substituted with electron donor groups exhibited a red-shift and a high oscillation factor compared with the unsubstituted molecule. Additionally, the ionization potential (IP), electron affinity (EA), reorganization energy (λ) and open-circuit voltage (Voc) of the molecules were evaluated. According to these values, the molecules show good photovoltaic properties, and efficient charge transfer for hole and electron and balanced charges.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-97072017000303637&lng=en&nrm=iso&tlng=e

Chirp-control of resonant high-order harmonic generation in indium ablation plumes driven by intense few-cycle laser pulses

We have studied high-order harmonic generation (HHG) in an indium ablation plume driven by intense few-cycle laser pulses centered at 775 nm as a function of the frequency chirp of the laser pulse. We found experimentally that resonant emission lines between 19.7 eV and 22.3 eV (close to the 13th and 15th harmonic of the laser) exhibit a strong, asymmetric chirp dependence, with pronounced intensity modulations. The chirp dependence is reproduced by our numerical time-dependent Schrödinger equation simulations of a resonant HHG by the model indium ion. As demonstrated with our separate simulations of HHG within the strong field approximation, the resonance can be understood in terms of the chirp-dependent HHG photon energy coinciding with the energy of an autoionizing state to ground state transition with high oscillator strength. This supports the validity of the general theory of resonant four-step HHG in the few-cycle limit

Ocena podatności wód gruntowych na zanieczyszczenia przy użyciu metody Kherici w regionie Collo na równinie Talezza (NE Algieria)

The intrinsic vulnerability of groundwater aquifers refers to their sensitivity to all contamination coming from soil surface irrespective of the nature of the polluting. In order to improve the protection of groundwater, there must be a reduction in the infiltration of contaminants towards the reservoir through the impacting factors determination of this phenomenon by means of research. There are collected models that include particular number of factors which allow the determination of a sign of groundwater vulnerability of all superficial pollutions. The goal of the study centers on ascertaining the state of vulnerability and the risk of groundwater pollution of the Collo region with a new proposed method by Kherici. Generally, assessment methods of vulnerability and the danger of groundwater pollution employ parametric systems with numerical quotation, cartographic superposition where the analytical methods are based on equations. In this study, we consider the combination of criteria dependent on natural factors (thickness of the unsaturated zone, geologic facies, degree of auto-purification) and the causes of groundwater vulnerability to man-made pollution (anthropogenic factors).Podatność podziemnych poziomów wodonośnych odnosi się do ich wrażliwości na zanieczyszczenia pochodzące z powierzchni gleby, niezależnie od ich charakteru. Dla ochrony wód gruntowych konieczne jest ograniczenie infiltracji zanieczyszczeń po ustaleniu czynników wpływu metodami badawczymi. Istnieją modele obejmujące szereg czynników, które umożliwiają określenie podatności wód gruntowych na zanieczyszczenia powierzchniowe. Celem badań było określenie stanu podatności i ryzyka zanieczyszczenia wód gruntowych w regionie Collo za pomocą nowej metody zaproponowanej przez Kherici. W metodach oceny podatności i zagrożenia zanieczyszczeniem wód gruntowych stosowane są zwykle parametryczny system numeryczny i kartograficzne nałożenia, w których metody analityczne bazują na równaniach. W pracy rozważano kombinację kryteriów zależnych od czynników naturalnych (miąższość strefy nienasyconej, facje geologiczne i stopień samooczyszczenia) oraz przyczyny podatności wód gruntowych na zanieczyszczenia antropogeniczne

Direct arylation of thiophenes via palladium-catalyzed C–H functionalisation at low catalyst loadings

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Palladium-catalyzed direct arylation of furans via C-H functionalisation at low catalyst loadings

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