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With the aim of realizing a Michelson interferometer working at 13.9 nm, we have developed a symmetrical beam splitter with multilayers deposited on the front and back sides of a silicon nitride membrane. On the basis of the experimental optical properties of the membrane, simulations have been performed to define the multilayer structure that provides the highest reflectivity--transmission product. Optimized Mo-Si multilayers have been successfully deposited on both sides of the membrane by use of the ion-beam sputtering technique, with a thickness-period reproducibility of 0.1 nm. Measurements by means of synchrotron radiation at 13.9 nm and at an angle of 45o provide a reflectivity of 14.2% and a transmission of 15.2% for a 60% s-polarized light, close to the simulated values. Such a beam splitter has been used for x-ray laser Michelson interferometry at 13.9 nm. The first interferogram is discussed. OCIS codes: 230.1360, 230.4170, 310.1860, 310.6860, 340.0340, 340.7450.

The article looks into the effect of water stress and girdling on intra-annual δ13C of tree-ring. A model is used, which is based on leaf discrimination during photosynthesis. One goal of the researchers is to examine the link between leaf and ring, in terms of the δ13C signal. Moreover, they will investigate the impact of the constraints on the ring growth, the intra-annual pattern of ring δ13C and the trunk respiration.