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The present research has been supported by the Institute of Solid State Physics, the University of Latvia within the framework of National Research Program IMIS2. [Grant numbers VPPI IMIS2, IMIS4]. ; The article presents a quantum kinetic framework to study interacting quantum systems. Having the constituting model Hamiltonians of two-band semiconductor and the photoexcited electron-hole pair, their quantum kinetic evolution has been revi-sited. Solution to this nonlinear problem of electron-hole interaction is obtained making use of the self-consistency loop between the densities of photoexcited electrons and holes and the pairwise interaction terms in the constituting model Hamiltonians. In the leading order, this approach supports the required isomorphism between the pairwise interaction and the birth and annihilation operators of the photoexcited electrons and holes as a desirable property. The approach implies the Hilbert space and the tensor product mathematical techniques as an appropriate generalization of the noninteracting electron-hole pair toward several-body systems. ; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

A new tabulation of electronic factors is reported for electron conversion for elements of Z from 5 to 126 and electronic factors for electron-positron pair conversion for elements of even Z from 4 to 100. The electronic factors for electron conversion, (E0), were calculated using a modified version of the CATAR program developed by Pauli and Raff with a relativistic-Hartree-Fock-Slater approach (Pauli and Raff, 1975). The electronic factors for electron-positron pair conversion, (E0), were calculated using the model developed by Wilkinson (1969). The data tables presented here cover all atomic shells up to R2 and transition energies from 1 keV to 6000 keV and from 1100 keV to 8000 keV for pair conversion. A comparison with previous electronic factor tabulations is presented. Ratios of experimental (E0) values for 83 E0 transitions in are compared to this tabulation. Two examples of how to use the tabulation to extract E0 strengths are also included. ; This work was supported by the Australian Research Council Discovery Grants DP140102986 and DP170101673. J.T.H.D. acknowledges support from the Australian Government Research Training Program .

A criação de pares elétron-pósitron é um dos vários mecanismos de interação do fóton com a matéria e o par pode ser produzido quando o fóton interage com um núcleo atômico ou com um elétron. As energias limiares do fóton kth para estas reações são respectivamente ~ 2m0c2 ou 4m0c2 (m0 é a massa de repouso do elétron e c é a velocidade da luz no vácuo). Um aspecto interessante da criação de par elétron-pósitron ocorre quando um fóton de energia muito baixa (k << m0c2) colide com um elétron ultra-relativístico (E >> m0c2). Nesta nota a cinemática da colisão entre um elétron e um fóton é revista e o aspecto particular e interessante da produção de tripleto quando elétrons ultra-relativísticos colidem com fótons de baixíssimas energias é brevemente descrito.

The understanding of spin dynamics and relaxation mechanisms in clean graphene, and the upper time and length scales on which spin devices can operate, are prerequisites to realizing graphene-based spintronic technologies. Here we theoretically reveal the nature of fundamental spin relaxation mechanisms in clean graphene on different substrates with Rashba spin-orbit fields as low as a few tens of μeV. Spin lifetimes ranging from 50 picoseconds up to several nanoseconds are found to be dictated by substrate-induced electron-hole characteristics. A crossover in the spin relaxation mechanism from a Dyakonov-Perel type for SiO substrates to a broadening-induced dephasing for hBN substrates is described. The energy dependence of spin lifetimes, their ratio for spins pointing out-of-plane and in-plane, and the scaling with disorder provide a global picture about spin dynamics and relaxation in ultraclean graphene in the presence of electron-hole puddles. ; This work has received funding from the European Union Seventh Framework Programme under grant agreement 604391 Graphene Flagship. S.R. acknowledges the Spanish Ministry of Economy and Competitiveness for funding (MAT2012-33911), the Secretaria de Universidades e Investigacion del Departamento de Economia y Conocimiento de la Generalidad de Cataluña and the Severo Ochoa Program (MINECO SEV-2013-0295). F.O. would like to acknowledge the Deutsche Forschungsgemeinschaft (grant OR 349/1-1). ; Peer Reviewed

The non-monotonic behavior of the electron repulsion energy and the inter-electronic distance, as a function of the internuclear separation, in the 3πu excited state of the hydrogen molecule has been assessed by explicit calculation and analysis of the electron-pair density distribution functions from high level ab initio full configuration interaction wave functions, for both the 3πu and the 1πu states. Additionally, Hund's rule as applied to these two states has been accounted for in terms of simple electronic shielding effects induced by wave function antisymmetrization ; This research has been funded by Euskal Herriko Unibertsitatea (the Univer- sity of the Basque Country), Eusko Jaurlaritza (the Basque Government) and the Spanish Office of Science and Technology (MINECO CTQ2014-52525-P)

We thank the Spanish MINECO, grant CTQ2015-65790-P, the FICyT, grant FC-GRUPIN-IDI/2018/000177, and the European Union FEDER for funding.

Based on the band structure of TlGaTe2 compound, the extrema of the valence and conduction bands were
determined and the tensor of the components of the inverse effective mass of electrons and holes was calculated.

We report on spin transport features which are unique to high quality bilayer graphene, in the absence of magnetic contaminants and strong intervalley mixing. The time-dependent spin polarization of a propagating wave packet is computed using an efficient quantum transport method. In the limit of vanishing effects of substrate and disorder, the energy dependence of the spin lifetime is similar to monolayer graphene with an M-shaped profile and minimum value at the charge neutrality point, but with an electron-hole asymmetry fingerprint. In sharp contrast, the incorporation of substrate-induced electron-hole puddles (characteristics of supported graphene either on SiO2 or hBN) surprisingly results in a large enhancement of the low-energy spin lifetime and a lowering of its high-energy values. Such a feature, unique to the bilayer, is explained in terms of a reinforced Dyakonov-Perel mechanism at the Dirac point, whereas spin relaxation at higher energies is driven by pure dephasing effects. This suggests further electrostatic control of the spin transport length scales in graphene devices. ; This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 696656, Graphene Flagship. S.R. acknowledges Funding from the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund [Project No. FIS2015- 67767-P (MINECO/FEDER)] and the Severo Ochoa Program (MINECO SEV-2013-0295). S.A. acknowledges support from the National Research Foundation of Singapore under its Fellowship programme (NRF-NRFF2012-01) and computational resources from the Centre for Advanced 2D Materials (an NRF midsized center). ; Peer Reviewed

Financial support by the Spanish "Ministerio de Economía y Competitividad MINECO" and the European Union through FEDER funds (Grants FIS2012-35880, FIS2015-64222-C2-1-P, FIS2015-64222-C2-2-P, and MAT2015-66586-R) and the Universidad de Alicante, is gratefully acknowledged.

9 pags., 4 figs., 1 tab. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; The photochemistry of the ethyl radical following excitation to the 3p Rydberg state is investigated in a joint experimental and theoretical study. Velocity map images for hydrogen atoms detected from photoexcited isotopologues CH3CH2, CH3CD2 and CD3CH2 at 201 nm, are discussed along with high-level ab initio electronic structure calculations of potential energy curves and non-adiabatic coupling matrix elements (NACME). A novel mechanism governed by a conical intersection allowing prompt site-specific hydrogen-atom elimination is presented and discussed. For this mechanism to occur, an initial rovibrational excitation is allocated to the radical permitting to access this reaction pathway and thus to control the ethyl photochemistry. While hydrogen-atom elimination from cold ethyl radicals occurs through internal conversion into lower electronic states followed by slow statistical dissociation, prompt site-specific Ca elimination into CH3CH + H, occurring through a fast non-adiabatic crossing to a valence bound state followed by dissociation through a conical intersection, is accessed by means of an initial ro-vibrational energy content into the radical. The role of a particularly effective vibrational promoting mode in this prompt photochemical reaction pathway is discussed. ; D. V. C. and S. M. P. contributed equally to the paper. D. V. C. thanks a contract from Spanish MINECO under the FPI predoctoral program. S. M. P. acknowledges nancial support from a postdoctoral contract of the Regional Government of Madrid (Spain) (Grant PEJD-2016/IND-3217). A. B. acknowledges the financial support of the Tunisian Ministry of Higher Education, Scientific Research, and Technology, of the Short Term Scientific Mission (STSM) program of the COST Action CM1401, and of LSAMA at the Universite de Tunis El Manar, that made possible research visits to the Instituto de Fısica Fundamental (CSIC, Spain). This work has been nanced by the Spanish MINECO (Grants No. CTQ2015-65033-P, FIS2016- 76418-P and FIS-2016-77889-R) and EU COST Action CM1401. This research has been carried out within the Unidad Asociada Quımica Fısica Molecular between the Departamento de Quiımica Fisica of Universidad Complutense de Madrid and CSIC. The facilities provided by the Centro de Laseres Ultrarrapidos at Universidad Complutense de Madrid are gratefully acknowledged. The Centro de Supercomputacion de Galicia (CESGA, Spain) and CTI (CSIC) are acknowledged for the use of their resources

This research was funded by European Social Fund (Project No 09.3.3-LMT-K-712-02-0105). DG acknowledges to the ERDF PostDoc grant No. 1.1.1.2/VIAA/1/16/177. ; In the search of universal host materials for organic light emitting diodes a new series of bipolar host materials containing methoxy-substituted carbazoles as the electron-donating and dibenzofuran as an electron-accepting units were designed and synthesized. Different linking topologies and number of methoxy groups attached to carbazolyl moiety were used to understand the impact of the strength of the donor moiety on the thermal, optical, photophysical, electrochemical and electroluminescent properties. The synthesized compounds exhibited relatively high thermal stability with 5% weight loss temperatures exceeding 378 °C and formed molecular glasses with high glass-transition temperatures ranging from 120 to 148 °C. High triplet energy values of 2.86–2.96 eV were estimated for dilute THF solutions at 77K. Hole and electron drift mobilities estimated using time-of-flight technique in solid layers approached 10−4 cm2V−1s−1 at high electric fields exceeding 3.6 × 105 V cm−1. The synthesized methoxy-carbazole based compounds were tested as hosts in electrophosphorescent and TADF organic light-emitting diodes reaching luminance of 53000 cd m−2 and external quantum efficiency of 12.5%, in the best case. ; European Social Fund 09.3.3-LMT-K-712-02-0105; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART² ; https://www.sciencedirect.com/science/article/pii/S0143720819311623