Nanoscale spectroscopy with polarized X-rays by NEXAFS-TXM

Abstract

International audienceNear-edge X-ray absorption spectroscopy (NEXAFS)1 is an essential analytical tool in material science. Combining NEXAFS with scanning transmission X-ray microscopy (STXM) adds spatial resolution and the possibility to study individual nanostructures2, 3. Here, we describe a full-field transmission X-ray microscope (TXM) that generates high-resolution, large-area NEXAFS data with a collection rate two orders of magnitude faster than is possible with STXM. The TXM optical design combines a spectral resolution of E/ΔE = 1 × 104 with a spatial resolution of 25 nm in a field of view of 15-20 µm and a data acquisition time of ~1 s. As an example, we present image stacks and polarization-dependent NEXAFS spectra from individual anisotropic sodium and protonated titanate nanoribbons. Our NEXAFS-TXM technique has the advantage that one image stack visualizes a large number of nanostructures and therefore already contains statistical information. This new high-resolution NEXAFS-TXM technique opens the way to advanced nanoscale science studies

Evidence for multifilamentary valence changes in resistive switching SrTiO3 devices detected by transmission X-ray microscopy

“…In contrast, both TiO 2 phases anatase and rutile show a double peak structure including a significant line with a splitting of more than 2.5 eV. 11,36,37 As no additional intensity is observed at this energy position, we can exclude the formation of TiO 2 phases. The Magnéli phases show very broad spectral features with only two clearly separated peaks 37 which would be in strong contrast to the observed four-peak structure.…”

“…Therefore, NEXAFS-transmission X-ray microscopy (TXM) is a powerful tool as it probes the whole film volume with a lateral resolution down to 25 nm. 11 For NEXAFS-TXM experiments photon transparent samples with a thickness below 100 nm are irradiated by photons in the soft X-ray regime. Fresnel lenses are used as objectives to obtain a magnified image of the sample.…”

“…At this endstation, Ti L-edge spectra can be measured with a spectral resolution of up to E/ E = 10 4 and a spatial resolution of 25 nm. 11 In order to record spectra with sufficient signal to noise ratio for each photon energy five separate images are acquired and summed up. Additionally the spectra are normalized by a nearby reference signal without Ti-signature to account for inhomogeneities in the beam intensity.…”

Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics

“…38,58,[173][174][175] Development of some of these optics has begun, but there is much more to achieve which requires innovative solutions and much improvement of the deposition and nanofabrication technologies. Advancement of these high precision optics will enable and push forward a range of frontier techniques, like resonant inelastic x-ray scattering, 116 nanoscale spectroscopy, 176,177 ultrafast dynamics study, [178][179][180] and quantum control. 181,182 On the other hand, the extremely bright XUV sources will also cause other problems for the optics, like a limited lifetime.…”

Ultrafast time resolved x-ray diffraction, extended x-ray absorption fine structure and x-ray absorption near edge structure

“…Therefore, linearly polarized x-rays have shown to be most suitable for the study of covalent systems such as low-Z molecules, polymers, and macromolecules with directional bonds. 107,108 Lately, NEXAFS spectra of benzene chemisorbed on Ag(110) surface have revealed that when the electric field vector E is normal to the surface, peaks due to the out-of-plane p orbital were seen, whereas in the case of parallel electric field vector, in-plane r orbital were observed. 109 In this paper, we shall describe briefly two time resolved NEXAFS studies.…”