A Compact Vibration Reduced Set-up for Scanning nm-XRF and STXM.

Abstract

Synchrotron radiation based scanning X-ray spectroscopy (XRS) can determine both elemental concentrations and chemical binding states with high spatial resolution down to the nanoscale. Within the last decade, the need for such high-resolution analytical methods in application fields such as life science, energy storage and conversion as well as climate protection has steadily increased. In order to quantify nanoelectronics, pharmaceuticals, biomolecules and medical imaging contrast agents in biological tissue and cells, the development and adaptation of traceable methodologies are crucial. XRS can be quantitative and recent advances in a novel kind of vibration reduced X-ray fluorescence (XRF) analysis have pushed the spatial resolution towards the 100 nm regime. This could provide the missing link for quantification across the length scales.There are only a few scanning X-ray microscopes that offer XRF analysis in combination with scanning transmission X-ray microscopy (STXM) such as Elettra-TwinMic (STXM and XRF); Diamond -I08 (STXM and XRF); PETRA III -P04 AnImaX (STXM and XRF); Advanced Light Source -11.0.2 (STXM and spectroscopy) and Canadian Light Source -10ID-1 (STXM and spectroscopy).With the advent of UHV-compatible piezo stages with nanometer resolution, it is possible to mount optical elements in a compact manner on a single platform. Relevant parts of any external vibrations might be reduced by such a single platform. The lay-out of its stages and related holders is to ensure amplitudes of relative vibrational movements to be smaller than the absolute ones by avoiding any resonance frequencies. We realized this approach in a compact translational and rotational set-up to align beamstops (or diagnostics), zone plates, order sorting apertures (OSA) and samples on a single mounting plate (see fig.1). This plate was mounted on a sample manipulator of non-microscopy equipment such as an XRF instrument in our case [1]. Furthermore, its overall size offers versatile areas of operation as the compact set-up can be readily inserted in a wide range of experimental (vacuum) chambers [2] through their load-locks. Our nm-XRF and STXM set-up is mounted on a 6-axis manipulator [1] which allows for an alignment of all three linear as well as all three rotational axes. The optics and the transmission sample are mounted on piezo positioning stages with 8 axes providing 1 nm resolution and encoder control on which the zone plate can be aligned in the X-Y plane (perpendicular to the optical axis) and the OSA as well as the transmission sample in X-Y-Z. The fluorescence samples are mounted on a 4-axis manipulator which can be moved in and out of the beam. The optical elements of the scanning X-ray microscope consist of an Au zone plate (with a diameter of 360 µm, an outer zone width of 25 nm and an integrated 50 µm central stop) and a 50 µm OSA. All measurements presented here are carried out with photon energy of 1500 eV at PTB's plane grating monochromator (PGM)

Quantification of Element Mass Concentrations in Ambient Aerosols by Combination of Cascade Impactor Sampling and Mobile Total Reflection X-ray Fluorescence Spectroscopy

“…In an ultrahigh-vacuum (UHV) chamber, a 9axis manipulator precisely tunes the incident angle θ between the X-ray beam and the sample surface. The fluorescence radiation emitted from the sample is detected using a calibrated silicon drift detector (SDD) [32], which is placed in the polarization plane and perpendicular to the propagation direction of the incident X-ray beam to minimize radiation scattered elastically or inelastically from the sample. The incident photon flux is monitored using a calibrated photodiode.…”

Quantitative Element‐Sensitive Analysis of Individual Nanoobjects

“…Nano-XRF Set-Up: The experimental nano-XRF set-up includes a zone plate, beamstop, order sorting aperture (OSA) and samples, all on one single and compact platform, [48] avoiding unwanted relative motions of the components, and thus reducing the sensitivity of the set-up to vibrations. It is described schematically in Figure 1 and can be directly mounted onto the sample stage of an existing ultra-high vacuum-compatible instrumentation for reference-free XRF.…”

Small target compatible dimensional and analytical metrology for semiconductor nanostructures using x-ray fluorescence techniques

“…Very similar experiments can be performed employing our setup for X-ray microscopy (XRM). 16,23 Here, we adopt a rather simple optical bench consisting of a pinhole, a fresnel zone plate and an order selection apperture (OSA) to enable XRM experiments at the PGM beamline. 24 The setup is mounted on a 6-axis sample manipulator.…”