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New Stable and Portable X-Ray Microspectroscope at KEK


At the high energy research accelerator KEK in Japan, Dr. Takeichi et al. designed a novel x-ray microspectroscope for high resolution composition analysis. The setup is comprised of 11 attocube ECS stepping positioners and a dedicated scanner for sample imaging. All the positioners are equipped with optoelectronic sensors and can be digitally controlled. The sample stage is stabilized via attocube’s interferometric FPS3010 sensor with a resolution of 25 pm. The whole four-stack-setup is compact enough to fit into a vacuum chamber of only 220×310×200 mm³. First measurements show the resolution of the new instrument to be approximately 40 nm.

 

      Y. Takeichi, et al; Rev.Sci.Instr. 87, 013704 (2016); doi: 10.1063/1.4940409
 
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Micromechanical Testing of Silver Nanowires


IThe small size of specimens often imposes significant challenges for preparation and testing. To overcome these difficulties, Prof. Horacio Espinosa’s group at the Mechanical Engineering Department in Northwestern University, USA, has developed a microelectromechanical system that allows mechanical testing of nanowires (see left figure). The system is capable of simultaneous four-point electrical measurements, therefore enabling piezoresistivity and -electricity measurements [1].
In order to mount the silver nanowires, they employed an attocube nanomanipulator, composed of three stacked ECS3030 positioners, one for each axis of movement. The nanomanipulator is positioned inside an SEM chamber and interfaced to the ECC100 piezo-controller outside the chamber.

 

      [1]  R.A. Bernal, et al., Small 10, 725 (2014).
 
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Cavity Enhanced Raman Microscopy


Raman spectroscopy has long been an indispensable tool for chemical analysis. However on the molecular level signals remain intrinsically small. Recently Th. Hümmer et al from the group of Prof. Hänsch achieved a more than sixfold amplification by putting the sample inside a tiny cavity. The cavity formed by the sample and a micro mirror on the tip of an optical fiber (1) can be scanned by a set of attocube’s ECSx3030 positioners to obtain images with close to optical resolution. The micro cavity is adjusted with some tens of pm resolution using another ECS positioner and an additional piezo. The signal is enhanced due to the Purcell effect stemming from the enhanced photon lifetime in a small cavity volume (2).
The group around Dr. Hunger at the LMU Munich applied the new method to some carbon nanotubes leading to clear pictures showing (3) the extinction cross-section and (4) the Raman signal of the G’ mode. “The cavity amplifies both the Raman scattering process as well as absorption from the sample. This allows one to combine ultrasensitive absorption microscopy with Raman imaging within a single measurement.”, explains Dr. Hunger. The group is confident to improve the method further boosting the signal enhancement by several orders of magnitude in the future.

 

      Th. Hümmer, J. Noe, M. Hofmann, T. W. Hänsch, A. Högele, and D. Hunger; Nature Communications 7, 12155, 12 July 2016