In this year’s highlight selection, the ESRF’s nanoprobe tools show their impact in fields ranging from bio-composites and semiconductor technology to extraterrestrial and environmental sciences and to cultural heritage studies. This is representative of the broad impact and the rapid development of the user community. Three upgraded beamlines (ID16A, ID16B and ID01) entered full user operation in 2015 marking a considerable step forward in the availability of nano-imaging methods. These beamlines join the already operational micro and nanodiffraction beamline ID13 and the X-ray microscopy beamline ID21 with its long standing tradition in spectromicroscopy. Gathering these five beamlines together to form the X-ray Nanoprobe Group (XNP-group) will generate a synergy that assures efficient development of world leading nanoprobe tools that will be made available to ESRF users.

This year’s article selection reflects both the fostering of established techniques making them available to non-expert users and the pioneering of new techniques of worldwide uniqueness. This demonstrates the variety and complementarity of our methods and experiments and also the necessary investment of our staff in the permanent evolution of our nanoprobes.

During this final phase of the ESRF’s Upgrade Phase I, ID01 started partial user operation interlaced with commissioning periods. The nanodiffraction endstation is routinely being used for the study of nanostructures and devices. Bragg coherent diffraction imaging, as presented in ref. [1], is one of the main techniques to benefit from the new endstation. This developing technique starts to show its full potential by shedding light on the displacement fields between two inversion domains in polar GaN. Along with this, a more flexible compromise between flux and beamsize should open the facility to more operando experiments examining structure-function relationships as presented by Bussone et al. [2].

ID13 has started operation of an Eiger 4M Pixel detector, highlighting the ESRF’s recent drive to invest in the most recent detector technology. The first experiments on time-resolved in situ nanocalorimetry of polymer-crystallisation have been successfully carried out with a 250 Hz framerate and a 10 µs readout time. Close to one millisecond resolution was achieved during the test phase of this device.

ID16A started full user operation in 2015, opening for users with nanotomography, including fluorescence tomography and ptychography, at two fixed energies, 17 and 33.6 keV. ID16B has been fully operational since 2014 and has recently started offering X-ray absorption nanospectroscopy with spatial resolution in the 50-100 nm range. A few user experiments have already been performed successfully. The beamline is also currently developing in situ devices for both high and low temperature studies. Together the ID16A/B tandem offers the ultimate resolution of a hard X-ray nanoprobe with beams in the 20-50 nm range and imaging methods typically applicable to heterogeneous structures such as biomaterials and fuel cells.

ID21 has opened a new side-branch for microdiffraction and microfluorescence 2D mapping that combines chemical and structural mapping within one instrument. This is further extending the micro-spectroscopy capabilities already offered in the tender X-ray range (2-9 keV) and the mid-infrared domain making ID21 best suited for investigating cultural heritage, geological, environmental and biological materials. As exemplified in the recent study of bioresorbable Mg implants, users are increasingly taking advantage of the combination of various micro and nano probes (here µXRF and µXANES at ID21 and µSAXS and µXRD at ID13). By offering complementary techniques, whether on a unique beamline or at several beamlines, a problem can be tackled with different views, and a full picture of the complex and interlaced physical, chemical or biological mechanisms can be obtained [3].

Extending the nanoprobes to the white beam regime, BM32 is routinely investigating poly- and monocrystalline samples. Its rainbow filtering technique [4], a new feature made available to users this year, allows determination of the full strain tensor, locally, without movement of the sample. Strain determination has become a necessity for materials such as highly strained semiconductors nanostructures that may represent new electronic properties in established materials. Guilloy et al. have demonstrated a material’s transformation by strain [5].

These examples draw a detailed picture of the structure and chemistry of samples from many different fields of applications, imaging parameters with a level of detail which often relied before on model calculations. The experimental findings presented here partially show the limits of such models and hence underline the importance of progress in experimental physics and new imaging methods in these fields. The coming years will see an increased effort in the development of user friendly software for our scanning probe microscopes as well as for the coherent reconstruction methods.

T.U. Schülli

 

References
[1] S. Labat et al., ACS Nano 9, 9210 (2015); doi: 10.1021/acsnano.5b03857.
[2] G. Bussone et al., Nano Lett. 15, 981-989 (2015); doi: 10.1021/nl5037879.
[3] T.A. Grünewald et al.., Biomaterials 76, 250 (2016); doi: 10.1016/j.biomaterials.2015.10.054.
[4] O. Robach et al., Acta Cryst. A 69, 164 (2013); doi: 10.1107/S0108767313000172.
[5] K. Guilloy et al., Nano Lett. 15, 2429 (2015); doi: 10.1021/nl5048219.