Suchergebnisse

L'abondance relative du deutérium et de l'hydrogène dans l'atmosphère solaire joue un rôle important dans les discussions sur la structure interne du soleil et sur les phénomènes de circulation au sein de cet astre.
L'auteur discute ce rôle et procède à une nouvelle estimation du rapport d'abondance de D et H en partant de raies de Balmer et de Paschen. Il semble bien que le deutérium soit moins abondant dans le soleil que sur la terre.

"Report Number: K-1585." ; "Subject Category: Chemistry (TID-4500, 25th Ed.)" ; ""AEC Research and Development Report." --from cover ; "Date of Issue: January 29, 1964." ; Includes bibliographical references (page 19). ; Acting under U.S. Government Contract ; Mode of access: Internet.

Abstract
In hybrid perovskite solar cells (PSCs), the reaction of hydrogens (H) located in the amino group of the organic A-site cations with their neighboring halides plays a central role in degradation. Inspired by the retarded biological activities of cells in heavy water, we replaced the light H atom with its abundant, twice-as-heavy, nonradioactive isotope, deuterium (D) to hamper the motion of H. This D substitution retarded the formation kinetics of the detrimental H halides in Pb-based PSCs, as well as the H bond-mediated oxidation of Sn2+ in Sn–Pb-based narrow-bandgap PSCs, evidenced by accelerated stability studies. A computational study indicated that the zero point energy of D-based formamidinium (FA) is lower than that of pristine FA. In addition, the smaller increase in entropy in D-based FA than in pristine FA accounts for the increased formation free energy of the Sn2+ vacancies, which leads to the retarded oxidation kinetics of Sn2+. In this study, we show that substituting active H with D in organic cations is an effective way to enhance the stability of PSCs without sacrificing photovoltaic (PV) performance. This approach is also adaptable to other stabilizing methods.

An indirect-drive cryogenic target is necessary for research in the field of laser thermonuclear fusion at a
megajoule energy level facility. Solid fuel layer in the target must meet high requirements: a roughness of the
inner cryolayer surface must be less than 1 µm, deviations from the sphericity and the concentricity must
be less than 1%. This paper describes the results of the research on meeting these requirements, notably,
cryolayer formation and its characterization. Due to the slow crystallization method of the deuterium layer
with its simultaneous heating by IR radiation it is possible to obtain deviations from the sphericity and the
concentricity of the inner cryolayer surface within limits of 2%, the roughness — within limits of 20 mkm.
Theoretical thermal calculations of the target construction are compared with experiment. The program
system was developed using the optical shadow method which makes it possible to measure liquid fuel when
filling the shell during the performance of the experiment, to perform the characterization of the solid cryogenic
layer parameters, to evaluate characterization results robustness.

This research was supported in part by Fundacao para a Ciencia e a Tecnologia (FCT), Portugal, through Projects No. PEstOE/FIS/UI0303/2011 and No. PTDC/FIS/117606/2010, financed by the European Community Fund FEDER through the COMPETE. P.A. and J.M. acknowledge support from the FCT (Portugal), under Contracts No. SFRH/BPD/92329/2013 and No. SFRH/BD/52332/2013. B.F., J.J.K., M.D., and R.P. acknowledge support from the European Research Council (ERC) (Belgium) through StG. Grant No. 279765. F.F. acknowledges support from the Austrian Science Fund (FWF) (Austria) through START Grant No. Y 591-N16. L.S. acknowledges financial support from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) (Belgium) under REA Grant Agreement No. 291734. A.A. acknowledges support from Swiss National Fond (SNF) (Switzerland) Grant No. 200020_159755. B.F. and R.P. would like to thank A. Beyer, L. Meisenbacher, and Th. Udem for illuminating discussions. ; Quantum interference between energetically close states is theoretically investigated, with the state structure being observed via laser spectroscopy. In this work, we focus on hyperfine states of selected hydrogenic muonic isotopes, and on how quantum interference affects the measured Lamb shift. The process of photon excitation and subsequent photon decay is implemented within the framework of nonrelativistic second-order perturbation theory. Due to its experimental interest, calculations are performed for muonic hydrogen, deuterium, and helium-3. We restrict our analysis to the case of photon scattering by incident linear polarized photons and the polarization of the scattered photons not being observed. We conclude that while quantum interference effects can be safely neglected in muonic hydrogen and helium-3, in the case of muonic deuterium there are resonances with close proximity, where quantum interference effects can induce shifts up to a few percent of the linewidth, assuming a pointlike detector. However, by taking into account the geometry of the setup used by the CREMA collaboration, this effect is reduced to less than 0.2% of the linewidth in all possible cases, which makes it irrelevant at the present level of accuracy. ; publishersversion ; published