Advanced Absorption Correction for 3D Elemental Images Applied to the Analysis of Pearl Millet Seeds Obtained with a Laboratory Confocal Micro X-ray Fluorescence Spectrometer

Abstract

We present a novel absorption correction approach for elemental distribution images obtained with a laboratory confocal micro X-ray fluorescence spectrometer. The procedure is suited especially for biological samples, as a constant dark matrix with a varying minor or trace element distribution is assumed. The constant absorption in the sample is extracted from depth dependent measurements. By using the concept of an effective excitation energy, depth-dependent, and element-specific excitation energy values are calculated. For each voxel of a full 3D measurement, a correction is performed taking into account the actual number of voxels in the excitation and detection path. As proof of concept, the embryonic region of pearl millet seeds is investigated. Data are measured from the top and bottom side, resulting in a good agreement after the application of the absorption correction procedure. The distribution of elemental micronutrients is compared in seeds of two pearl millet genotypes. The corrected images illustrate different localization patterns of the micronutrient elements in pearl millet seed tissues.

A novel confocal XRF-Raman spectrometer and FPM model for analysis of solid objects and liquid substances

“…If the matrix contains low-atomic-number elements in the range of atomic numbers of 1 # Z # 11 the characteristic X-ray lines of these elements can be detected with only thin-window or windowless detectors. 15 These elements are undetectable with conventional ED detectors equipped with a Be window, and therefore this part of the sample is called in related literature a dark [24][25][26][27] or residual 28 matrix. For the FPM calculation the energy dependent absorption function of the dark matrix has to be known.…”

Selective mineral transport barriers at Cuscuta‐host infection sites

“…The commercial MXRF spectrometer (Bruker M4 tornado) was equipped with a Rh microfocus X‐ray tube, a polycapillary lens to focus the radiation and a SDD detector (Lachmann et al ). In front of a second SDD a second polycapillary lens was mounted perpendicular to the first, thus creating a confocal MXRF setup which enabled three‐dimensional‐resolved measurements with a resolution of 30 µm at Fe Kα (Mantouvalou et al ). A fisheye camera with two magnification stages (10× and 100×) was used for positioning of the sample.…”

“…Increasing the mineral concentrations in edible crops, e.g. is a big task in the strive for food security (White and Broadley , Mantouvalou et al ). An infection by Cuscuta species often causes severe crop yield losses (Costea and Tardif ), which in part seems to be related to the depletion of photosynthates in its hosts.…”

Reverse Monte Carlo iterative algorithm for quantification of X‐ray fluorescence analysis based on MCNP6 simulation code

“…Those parts of the sample matrix constituted by these low-Z number of elements is called as dark matrix. 7,23 In RMC-XRF calculations, the matrix-effect caused by the dark matrix must be considered in the numerical calculations. However, in this project, we have only investigated the applicability of the MCNP6 simulation code in RMC mode for simple conditions analyzing metal SRM samples without dark matrix.…”