MAT science Week

Extensive characterization is needed to understand the physicochemical properties of polymeric membranes that are used for water purification. 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...

Metallic nanowires have various applications in the fields of sensorics, electronic or energy harvesting. These applications are based on the excitation of collective electronic oscillations in the nanowires called surface plasmons that are generated by the electric field of light. Whereas the resonant plasmonic wavelength of a spherical Au particle is located in the visible light range, for...

Tuning plasmonic and electrical properties of nanostructures is of great importance for exploring new applications. Based on ion track technology, we have developed several interesting nanostructures, including nanowires, nanocones, metasurface, and sharp ridge-rich hierarchical nanopillars. Taking benefit from such a unique technology, we demonstrate that the key parameters of nanostructures,...

A setup for in-situ Rutherford Backscattering Spectrometry (RBS) has been installed at the 2 MV Van-de-Graaff accelerator at the Ion Beam Center (IBC) of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Online analysis of solid-liquid interfaces as well as electro-chemistry experiments are conducted by this technique. A Si3N4 window separates the liquid from the vacuum in the RBS chamber. A...

Electronic excitation caused by swift heavy ions (SHI) in solids often leads to permanent changes in the crystal structure, either by direct excitation or electron-phonon coupling following the initial electronic excitation. At single crystal surfaces, this leads to modifications of the topography which can be detected in real space by means of scanning probe techniques. For monoatomic...

A new efficient negative ion source for Accelerator Mass Spectrometry (AMS) is being built to quantify the ratios of long-lived cosmogenic radionuclides in micrometeorites. Measuring these extremely small ratios is at the technological limits of present AMS systems. The new source is designed specifically to provide a higher AMS detection sensitivity by having an optimal ion-optics design,...

The one-neutron halo-nucleus Be-11 decays via beta-minus to the stable nucleus B-11 (t1/2=13.76 s). In rare cases a subsequent emission of a proton leads to the unstable nucleus 10Be. Theoretical calculations predict a branching ratio of this rare decay channel of below 1E-7. With the capability of AMS in measuring ultra-low isotopic ratios (Be-10/Be-9 < 1E-15) the branching ratio of...

Half-lives of routine accelerator mass spectrometry (AMS) nuclides typically range from thousands to millions of years. We measured short-lived $^{7}$Be (T1/2 = 53.2 d) at the DREsden AMS-facility (DREAMS) [1] as low as 90 mBq, which can be challenging for rapid $\gamma$-counting. Simultaneous determination of $^{7}$Be and $^{10}$Be (T$_{1/2}$ = 1.387 Ma) via AMS is advantageous for...

The ECHo (Electron Capture in Holmium Experiment) collaboration aims at measuring the electron neutrino mass by recording the spectrum following electron capture of 163Ho using metallic magnetic calorimeters. The radioisotope 163Ho (t1/2 = 4570 a) is produced by neutron capture from enriched 162Er in the Institute Laue-Langevin high-flux nuclear reactor. After chemical separation the important...

New experimental results regarding the mass and charge state distribution of material sputtered under irradiation with swift heavy ions suggest fundamental differences between the particle ejection mechanisms under electronic and nuclear sputtering conditions. In order to illustrate the difference, computer simulations based on molecular dynamics were performed to model the surface ejection...

We used 1-2 MeV rare-gas (He, Ar, Kr) ion beams to study and modify the surface and interfaces of thin films of materials with a high potential for applications, such as magnetite Fe3O4 (spintronic devices/sensors at room temperature), titanium oxynitrides TiNxOy (photocatalysis), Ti/V and their oxides-based films (hydrogen storage), uranium nitride UN (nuclear fuels), highly-ordered Pd-Fe...

In thin film growth using physical vapor deposition methods like e.g. magnetron sputtering, energetic particles are involved in the deposition process acting either directly as film-forming components or indirectly as impinging particles which deliver additional energy and momentum to the surface of the growing film. With most of these techniques, there exists a mixture of all these particle...

An increasing interest is focused on the epitaxial magnetite (Fe3O4)-based films due to their potential application as spin dependent transport devices. We present our study of the composition and layer structure of the single-layer Fe3O4 and bi-layer Fe3O4/Fe films epitaxially deposited on MgO(001) substrates. We focus on underlining the influence of thermal annealing and ion beam...

To extract chemical compositions and layer thicknesses of layered samples from Ion Beam Analysis (IBA) spectra experimentalists typically have to simulate a theoretical spectrum for an initial target configuration and compare the outcome to the measured data followed by the successive re-adjustment of the target model until simulation result and experimental spectrum fit each other. For...

Active, widely tunable optical materials have enabled rapid advances in photonics and optoelectronics, especially in the emerging field of meta-devices. Of the tunable optical materials, one of the most prolifically studied is the VO2, which undergoes a reversible IMT as the temperature reaches a critical temperature of approximately 67°C due to strong electron correlations. Energetic ion beams...

A time-of-flight mass spectrometer to investigate sputtered material under swift heavy ion bombardment installed at the M-Branch of the UNILAC beam line is not only capable of getting mass resolved information about sputtered secondary ions, i.e., ionized atoms, clusters and molecules leaving the irradiated surface, but also allows the detection of their neutral counterparts by means of laser...

Hyperdoping has emerged as a promising method for designing semiconductors with unique physical properties. In general, these properties are primarily determined by the lattice location of the impurity atoms in the host material. In this contribution, the lattice location of implanted chalcogens in Si was experimentally determined by means of Rutherford backscattering/channeling (RBS/C)....

Glass is a function material with free volume. The gas diffusion coefficient in glass is sensitive to atom size and temperature. This feature could be used as a functional filter of gases. In order to enhance Ar diffusion coefficient in glass without changing mechanical property, heavy ion irradiation was applied in this work. Hollow glass microspheres was irradiated with the 15 MeV Si6+, at...

Solid-state nanofluidic pores have been attracting considerable attention of scientific community because of their structural and chemical resemblance with biological ion channels for mimicking biological process in living systems. Compared to ion channels, synthetic nanopores exhibit high stability, control over pore dimensions (size and geometry) and their surface chemical properties can be...

In-situ X-ray diffraction measurements following the details of ion nitriding of stainless steel have been developed during the last 5 years. Nevertheless, the amount of local information is limited as diffusion and relaxation processes due to the elevated temperature during the process will lead to dynamic processes difficult to be resolved as a function of depth. On the other hand,...

Structuring of surfaces through ion beam irradiation can be used to create self organizing dune-like waves, dimples, flat surfaces or chaotic patterns. The final structures are a result of the interplay of sputtering, redeposition, projectile implantation, transport and viscous flow, void/bubble formation and the initial surface conditions. Accurate simulations of structuring are possible...

Silicon nanopillars down to a diameter of ~20 nm and up to an aspect ratio 3 have been exposed to high-fluence irradiation of 50 keV Si$^+$ ions. When the pillars are kept at room temperature (RT) they change their shape drastically under 10$^{16}$ Si$^+$cm$^{-2}$ irradiation: They become bell-shaped, i.e. their heights decreases and their diameters increases strongly. To understand this...

Mn doped III-V compounds semiconductors have been regarded as the prototype of ferromagnetic semiconductors. However, their preparation presents a big challenge due to the low solubility of Mn. In this talk, I will show how ion beams can be used in fabricating and understanding ferromagnetic semiconductors. First, ion implantation followed by pulsed laser melting (II-PLM) provides an...