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23AIST TODAY 2013-1Kazutomo SUENAGANanotube Research CenterAIST TODAY Vol.12 No.12 p.14 (2012)X-ray spectroscopy captures signals from single atomsImproved sensitivity realized single atom identification We have developed a high sensitivity X-ray detector and demonstrated the detection of the characteristic X-ray signals from single Er atoms in energy dispersive X-ray spectroscopy. The intensities of Er L and M lines from a single Er atom were extremely weak in contrast to the N-edge of electron energy-loss spectroscopy, which implies the intrinsic difficulty to sense single atoms in X-ray spectroscopy. Nevertheless, this work will certainly ensure the possibilities to obtain X-ray spectra from single atoms and to identify single atoms in the sample.Metrology and Measurement ScienceUtilization of slow positrons under atmospheric conditions based on a microbeam techniqueTo realize in-situ evaluation of intermolecular spaces in functional thin filmsWe have developed a controlled-environment positron probe micro-analyzer. This system can be used with the positron annihilation lifetime technique to evaluate open spaces such as atomic- and molecular-level defects, holes, and pores of functional thin films in an ambient gas at atmospheric pressure, i.e., in conditions which are close to the actual working environment. In this system, positrons are generated in a vacuum and formed into a focused, short-pulsed beam with low, variable energy. The beam is extracted via a thin vacuum window into the atmosphere, and then injected into the film sample, so that the positrons stop near the surface. By using this system, nondestructive evaluation of the intermolecular spaces for a polymer thin film with a thickness of a few hundred nanometers in nitrogen gas with controlled, variable, relative humidity has been achieved.Schematic of the method used to extract the slow positron beam into the atmosphere(a) The developed analytical microscope (at Kyushu University) and (b) the schematic of the experimentNanotechnology, Materials and Manufacturing(a)Probe current: ~ 200 pA ~ 50 mrad~ 0.8 srEDX detector 100 mm2 SDD (Centurio)Mo grid 10 degree tilt5 mm apertureEELS (GIF Quantum) ~ 40 mrad(b)Positron beam(Large diameter: ~10 mm) VacuumLarge window(relatively thick: ~10 µm)Thin film samplePositron beam(Small diameter: ~0.1 mm)VacuumSmall window (relatively thin: ~0.03 µm) Thin film sampleConventional method: Extraction of large diameter beamPositrons cannot stop within a thin film sample because they are extracted into atmosphere with high speed (high energy). AtmosphereAtmosphereNewly developed method: Extraction of small diameter beamPositrons can stop within a thin film sample because they are extracted into atmosphere with low speed (low energy).Nagayasu OSHIMAResearch Institute of Instrumentation FrontierKenji ITOMetrology Institute of JapanAIST TODAY Vol.12 No.12 p.15 (2012)

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