Germanium collimating micro-channel arrays for high resolution, high energy confocal X-ray fluorescence microscopy

Abstract

Abstract. Confocal x-ray fluorescence microscopy (CXRF) allows direct detection of x-ray fluorescence from a micron-scale 3D volume of an extended, unthinned sample. We have previously demonstrated the use of a novel collection optic, fabricated from silicon, that improves the spatial resolution of this approach by an order of magnitude over CXRF using polycapillaries. The optic, called a collimating channel array (CCA), consists of micron-scale, lithographically-fabricated arrays of collimating channels, all directed towards a single source position. Due to the limited absorbing power of silicon, the useful energy range of these optics was limited to fluorescence emission below about 10 keV. Here, we report fabrication of CCAs from germanium substrates, and demonstrate their practical use for CXRF up to 20 keV. Specifically we demonstrate a nearly energy-independent critical spatial resolution d R of 2.1±0.17 µm from 2-20 keV, as well as excellent background reduction compared to silicon-based CCAs throughout this energy range. Design details of the optic and background-reduction holder are described. Two versions of the optic are now available upon request at the beamline 20ID-B, Advanced Photon Source (APS) -Argonne National Laboratory.

Plasmonic nanorod probes’ journey inside plant cells forin vivoSERS sensing and multimodal imaging

“…In contrast to polycapillaries, recently developed Collimating Channel Arrays (CCAs) provide both an overall improvement in resolution and, importantly, spatial resolution that is invariant with the X-ray fluorescence energy. 72 The new CXRF microscopy capability at sector 20-ID at the APS, enabled by CCAs, are capable of achieving depth resolution of 2 μm. In addition, CXRF microscopy significantly improves the signal-to-noise ratio by rejecting background scattering, thus increasing the limit of detection of fluorescent X-rays.…”

“…CXRF experiments measurements making use of CCAs were made at the 20-ID beamline of the APS [72][73][74] on the same three samples that were previously measured with 2D XRF at the MRCAT/EnviroCAT beam line at the APS. An incident X-ray energy of 12 keV was used for the measurements.…”

OPT3 Transports Copper to the Phloem, Mediates Shoot-to-Root Copper Signaling and Crosstalk Between Copper and Iron Homeostasis inA. thaliana

“…The beamline monochromator and focusing optics were employed to deliver 3×10 11 photons/second in a 1×1 µm 2 beam, with incident beam energy of 10.0 keV and bandwidth of approximately 1 eV. The confocal geometry was achieved by placing a collimating channel array (CCA) (Agyeman-Budu et al, 2016) onto a single-element Vortex SDD detector perpendicular to the beam. The sample stage was oriented such that the horizontal translation axis of the stage is 35 degrees from that of the incident beam, and 55 degrees from the detector axis.…”

Evaluation of mercury stabilization mechanisms by sulfurized biochars determined using X-ray absorption spectroscopy

“…The XRF spectra were collected by a Si-drift Vortex detector perpendicular to the incident beam. A Ge optical unit (lithographically fabricated spoked channel array) was mounted in front of the detector to complete the confocal geometry [47][48][49].…”