Coulomb excitation of 102 Ru with 12 C and 16 O

The Coulomb excitation of 102Ru was performed with beams of 12C and 16O ions. The beam particles scattered at forward angles were momentum analyzed with a magnetic spectrograph. The resolution achieved enabled the populations of the 2+ 1 state, the unresolved 2+ 2 /4+ 1 , and 2+ 4 /3− 1 , doublets of states, and the 3− 2 state to be determined as a function of the scattering angle. These populations are compared with GOSIA calculations, yielding B(E2; 2+ 1 → 0+ 1 ) = 41.5 ± 2.3 W.u., B(E2; 2+ 2 → 0+ 1 ) = 1.75 ± 0.11 W.u., B(E3; 3− 1 → 0+ 1 ) = 31.5 ± 3.5 W.u., and B(E3; 3− 2 → 0+ 1 ) = 6.8 ± 0.5 W.u. The B(E3; 3− 1 → 0+ 1 ) value is significantly larger than previously measured. The weakly populated 2+ 3 state, presumed to be a member of the band built on the 0+ 2 state, was observed clearly for a single angle only, and a fit to its population results in B(E2; 2+ 3 → 0+ 1 ) = 0.053 ± 0.011 W.u. Using the known γ -ray branching ratios for the 2+ 3 level, the B(E2; 2+ 3 → 0+ 2 ) value is calculated to be 18 ± 4 W.u., substantially less than the B(E2; 2+ 1 → 0+ 1 ). This suggests that the deformation of the 0+ 2 state is lower than that of the 0+ 1 state. The results are compared with beyond-mean-field calculations with the Gogny-D1S interaction using the symmetry-conserving configuration-mixing method

Elemental Depth Profiling of Chlorinated Polyamide-Based Thin-Film Composite Membranes with Elastic Recoil Detection

The chlorine resistance of nanofiltration and reverse osmosis membranes is of high importance in the water treatment industry. Elastic recoil detection (ERD) is now presented as a powerful tool to uniquely provide elemental depth profiles, including hydrogen, of NaOCl-treated polyamide-based thin-film composite (TFC) membranes. The influence of pressure, pH, and chlorine feed concentration on the volume-averaged Cl uptake, the location of chlorine throughout the membrane, and the z-gradient in the Cl/N ratio is demonstrated. The results suggest that (i) higher volume-averaged Cl uptakes are achieved at higher chlorine doses and at acidic pH; (ii) chlorination is mostly restricted to the top layer; (iii) a gradient in the Cl/N ratio exists along the membrane depth; and (iv) the shape of this gradient is influenced by the chlorination pH and the applied pressure. Conclusions on the chlorination mechanisms could also be deduced. Conversely, no conclusive relationships between H fractions and Cl uptake could be drawn, even though changes in the H content after chlorination were observed. To corroborate these results and fully exploit the potential of ERD, the exact microstructure of the (chlorinated) TFC membranes should be better understood.status: publishe

Analysis of Ultra-Thin HfO2/SiON/Si(001): Comparison of Three Different Techniques

Composition depth profiling of HfO2 (2.5 nm)/SiON (1.6 nm)/Si(001) was performed by three diffetent analytical techniques: high-resolution Rutherford backscattering spectroscopy (HRBS), angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and high-resolution elastic recoil detection (HR-ERD). By comparing these results we found the following: (1) HRBS generally provides accurate depth profiles. However, care must be taken in backgroud subtraction for depth profiling of light elements. (2) In the standard AR-XPS analysis, a simple exponential formula is often used to calculate the photoelectron escape probability. This simple formula, however, cannot be used for the precise depth profiling. (2) Although HR-ERD is the most reliable technique for the depth profiling of light elements, it may suffer from multiple scattering, which deteriorates the depth resolution, and also may cause a large background

Full elemental depth-profiling with nanoscale resolution: The potential of Elastic Recoil Detection (ERD) in membrane science

© 2018 Elsevier B.V. Extensive characterization is needed to understand how the physicochemical properties of polymeric membranes are related to their transport properties and to allow optimization of membrane design. Currently, most techniques characterize the (near)-surface region of the membrane, even though its bulk obviously also plays a significant role in the final membrane performance. To achieve depth-profiles of the elemental composition of both integrally skinned asymmetric (ISA) and thin-film composite (TFC) membranes, elastic recoil detection (ERD), an ion beam analysis technique, is now introduced to the field as a potentially highly valuable tool to complement for instance XPS, EDX or RBS. The determination of the complete elemental composition, importantly also including hydrogen, as function of the membrane thickness allows to gain knowledge about its depth-heterogeneity at an impressive combination of ca. 15 nm resolution with ppm-range sensitivity. This very low detection limit additionally allows the analytical quantification of e.g. remnants from synthesis conditions. The potential as well as the pitfalls of ERD as a novel, valuable technique for membrane characterization are critically discussed and illustrated by the determination of the thickness of polyamide-based top-layers of TFC membranes.status: publishe

Sputtering of LiF and other halide crystals in the electronic energy loss regime

International audienceSputtering experiments were performed by irradiating LiF, NaCl, and RbCl crystals with various swift heavy ions like S, Ni, I, Au with energies between 60 and 210 MeV, C$_{60}$ clusters between 12 and 30 MeV or Pb ions between 730 and 6040 MeV. Sputtered species are collected on arc-shaped catchers and subsequently analyzed by elastic recoil detection analysis or Rutherford backscattering analysis. The study focuses on angular distributions and total yields for LiF and covers a broad range of experimental parameters including cleaved or rough sample surfaces, ion fluence, beam incident angles, and different ion velocities leading to electronic energy loss (S$_{e}$) values from 5 to 45 keV/nm. In most cases, the angular distribution has two components, a jet-like peak perpendicular to the surface sample superimposed on a broad isotropic cosine distribution whatever is the beam incident angle. The observation of the jet depends mainly on the surface flatness and angle of ion incidence. However, the jet does not appear clearly when irradiated with C$_{60}$ cluster. The sputtering yield is stoichiometric and characterized by huge total yields of up to a few 10$^{5}$ atoms per incident ion. The yield follows a power law as function of electronic energy loss, Y follows an exponential law with S$_{e}^{n}$ with n ~ 4. While the azimuthal symmetry for sputtering is observed at low ion velocity (~1 MeV/u), it seems to be lost at high velocity (>4 MeV/u). The data provide a comprehensive overview how the angular distribution and the total sputtering yield scale with the energy loss, beam incidence angle and ion velocity. Complementary experiments have been done with NaCl and RbCl targets confirming the observation made for LiF.[graphic not available: see fulltext][graphic not available: see fulltext