Investigations of the magnetic properties of CeRh<SUB>2</SUB>Si<SUB>2</SUB> using lattice parameter, L<SUB>III</SUB> edge and extended X-ray absorption fine structure measurements

The lattice parameters of tetragonal CeRh2Si2 are anomalous compared with those of the other members of the series CeM2Si2 (M &#8801; Ru, Rh, Pd and Ag). Measurements of the susceptibility of CeRh2Si2 as a function of temperature in the range 15-300 K reveal interesting features. At high temperatures the susceptibility obeys a Curie-Weiss law with an effective moment per cerium ion that is 20% higher than that of the free Ce3+ ion. There is a cusp-like peak at about 37 K and a relatively smaller peak at 5.2 K. The lattice parameters a and c show a slight decrease between 300 and 40 K and a rather small increase between 40 and 12 K. The LIII absorption edge and the extended X-ray absorption fine structure spectra are unchanged between 20 and 300 K. This clearly indicates that the valence of the cerium ion does not change and that the first-nearest-neighbour environment (eight rhodium atoms and eight silicon atoms) of the cerium ion is not affected by the transition at 37 K

DEPENDENCE OF THE ELECTRONIC STRUCTURE OF YBa2Cu3O7-∂ CERAMICS ON OXYGEN STOICHIOMETRY : A PHOTOEMISSION AND PHOTOABSORPTION STUDY

X-ray photoemission (XPS) and X-ray absorption (XAS) have been performed on YBa2Cu3O7-∂ ceramics as a function of ∂ (0.1 < ∂ < 0.7). The results show the modifications of the Cu electronic structure around the superconducting-semiconducting transition. XPS and XAS experiments give complementary informations allowing the identification of Cu+, Cu2+ and the so-called Cu3+ configurations as a function of ∂

Réflectomètre à large spectre EUV pour la métrologie d'optiques

Le Laboratoire Charles Fabry conçoit de nombreuses optiques dont certaines pour les applications dans le spectre EUV. Pour les besoins de caractérisation, il est nécessaire de posséder une métrologie à la longueur d'onde d'utilisation proche des moyens de fabrication. Ceci permet d'étudier les composants dès leur conception et de caractériser les optiques. Nous présentons ici les performances d'un réflectomètre automatisé EUV large spectre. Il a été développé dans le cadre de la centrale CEMOX$^1$, initiée par le pôle PRaXO$^2$

Stabilité thermique des performances spectrales de miroirs EUV

Le développement de miroirs EUV résistant à des températures élevées représente un enjeu important pour la lithographie EUV. Nous avons optimisé et déposé plusieurs empilements multicouches Mo/SiC/Si/SiC en faisant varier les épaisseurs respectives de SiC aux deux interfaces. Ces différents types d'empilements ont ensuite subi une série de recuits thermiques pour évaluer l'influence des deux paramètres temps et température de recuit, sur les performances spectrales. Des structures stables après un recuit de 200 h à 400 °C ont été optimisées et caractérisées

Journal of quantitative spectroscopy & radiative transfer

International audienceHigh harmonic amplification is shown in an optical-field ionized X-ray laser. The 4d-4p X-ray line of Kr8+ at 32.8 nm, which has a close match to the 25th harmonic of the infrared laser, was amplified up to 200 times. The energy-extraction regime was also achieved, which depended on the level of seeding. This second-generation X-ray laser is fully polarized, has low divergence and shows a high degree of coherence. The duration is also expected to be short, fulfilling the requirements for an ultra-intense tabletop X-ray laser. Conditions for higher energy output are also suggested

Journal of quantitative spectroscopy & radiative transfer

International audienceHigh harmonic amplification is shown in an optical-field ionized X-ray laser. The 4d-4p X-ray line of Kr8+ at 32.8 nm, which has a close match to the 25th harmonic of the infrared laser, was amplified up to 200 times. The energy-extraction regime was also achieved, which depended on the level of seeding. This second-generation X-ray laser is fully polarized, has low divergence and shows a high degree of coherence. The duration is also expected to be short, fulfilling the requirements for an ultra-intense tabletop X-ray laser. Conditions for higher energy output are also suggested

The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager (Corrigendum)

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The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager

Context. The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out of the ecliptic. Solar Orbiter will advance the "connection science" between solar activity and the heliosphere. Aims: With EUI we aim to improve our understanding of the structure and dynamics of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives. Methods: The EUI consists of three telescopes, the Full Sun Imager and two High Resolution Imagers, which are optimised to image in Lyman-α and EUV (17.4 nm, 30.4 nm) to provide a coverage from chromosphere up to corona. The EUI is designed to cope with the strong constraints imposed by the Solar Orbiter mission characteristics. Limited telemetry availability is compensated by state-of-the-art image compression, onboard image processing, and event selection. The imposed power limitations and potentially harsh radiation environment necessitate the use of novel CMOS sensors. As the unobstructed field of view of the telescopes needs to protrude through the spacecraft's heat shield, the apertures have been kept as small as possible, without compromising optical performance. This led to a systematic effort to optimise the throughput of every optical element and the reduction of noise levels in the sensor. Results: In this paper we review the design of the two elements of the EUI instrument: the Optical Bench System and the Common Electronic Box. Particular attention is also given to the onboard software, the intended operations, the ground software, and the foreseen data products. Conclusions: The EUI will bring unique science opportunities thanks to its specific design, its viewpoint, and to the planned synergies with the other Solar Orbiter instruments. In particular, we highlight science opportunities brought by the out-of-ecliptic vantage point of the solar poles, the high-resolution imaging of the high chromosphere and corona, and the connection to the outer corona as observed by coronagraphs