Ion beam analysis laboratory and laboratory for nanomaterials 

The main development tasks at the 5-MV tandem accelerator TAMIA in 2014 concentrated on the installation and testing of the sample preparation and transport system for gaseous CO2 that is fed into the hybrid AMS (GAS-MCSNICS) ion source. The first tests with gaseous samples were successfully performed and produced 12C ion beam currents of about 5 µA. Using the same ion source in AMS measurements with graphitized samples yielded routinely an accuracy of better than 0.3% for the radiocarbon concentrations. These conventional AMS measurements, at 3-MV terminal voltage and charge state of +3, were performed through the year as four-day campaigns every second weekend (Friday to Tuesday). For all other experiments, the negative ions were extracted from the MISS ion source. The accelerated ions ranged from protons (at energies from 1.50 MeV to 10 MeV) to 197Au (stripped to charge state of +15 to reach the final energy of 80 MeV). An external-beam setup (in-air-PIXE) employing thin Si3N4 exit foils for 3-MeV protons was designed and constructed for the measurement of elemental composition in archaeological samples. About one-third of the beam time of TAMIA was devoted to the TOF-ERDA experiments on thin ALD samples. Ion beams of 35Cl, 37Cl, 79Br, and 127I at energies between 32 and 55 MeV were employed in TOF-ERDA. As a complementary technique, Rutherford backscattering with 7Li, 12C, and 28Si ions was used in some cases, e.g., for separation of Sn and Pb signals in a composite sample. Beams of 10-MeV protons and 23-MeV 12C were used for the study of irradiation effects in various materials, including graphene-oxide, carbon nanotube composites and SiC (followed by positron annihilation spectroscopy studies in collaboration with Aalto University).

The only tank opening of TAMIA during 2014 was caused by the wearing-out of the belt that runs the alternator powering-up the recirculating turbo pump at the high-voltage terminal. The service break then also included routine tests of the voltage-dividing resistor chain and adjustment of the spark gap of the high-pressure, high-voltage feedthrough of the charging belt. Furthermore, remote fiber-optic computer control for the charge-exchange gas at the high-voltage terminal was installed, enabling a much faster response possible than before. Minor service tasks and the further development of the control software were performed either during the experiments or between them.

The 500-kV ion accelerator KIIA was running very reliably in 2014 at all accelerating voltages, and only minor routine service, mostly on the ion sources was required. The accelerator was used almost exclusively for ion-beam implantation and irradiation experiments with ions ranging from 10-keV protons to 500-keV 127-iodine ions. As a new development, the iodine ion beams were generated in the Penning ion source by feeding it with iodine vapor from an external vial filled with elemental iodine. A project for installation of a computer control and automation system for KIIA was initiated. The lessons learned in the development and implementation of a similar system for TAMIA greatly facilitate the work.

During the past year, the main activity of the Laboratory for Nanomaterials was within the Center of Excellence project in Atomic Layer Deposition (CoE ALD) funded by the Academy of Finland. Novel multifunctional materials were in focus, aiming, first of all, at synthesis and studying of ultra-thin multiferroic films and nanostructured surfaces. Bismuth ferrite multiferroic films have been grown by ALD and analyzed by different techniques including also by the recently installed unique spectrometer combining Secondary Ion/Neutral Mass-Spectrometry and X-ray Photoelectron Spectroscopy in a single instrument (SIMS/SNMS-XPS). The synthesized films were found to show very good dielectric properties, exhibit peculiar magnetic behavior but they turned out to be rater poor ferroelectrics. In order to be of interest for practical applications, the latter is to be improved and this will be in focus of the future research.

The new SIMS/SNMS-XPS spectrometer turned out to be of unexpectedly high interest for internal and external users. While SIMS/SNMS enables surface analysis with a record sensitivity in the ppb range and depth profiling, XPS enables complementary surface chemical state characterization. The facility was actively employed in the following projects (in addition to already mentioned CoE ALD): EU and TEKES funded EUROFUSION project (materials for fusion reactors, collaboration with VTT); development of radiation hard silicon detectors (in collaboration with HIP). Interaction of self-assembled monolayers with nanoclusters deposited on a surface and argon ion irradiation-induced morphological instability of bare and thiol-functionalized Au(111) surfaces were studied.