Dept. of Analytical Chemistry, University of the Basque Country (UPV/EHU), 48940, Leioa, Spain.
Dept. of Analytical Chemistry, University of the Basque Country (UPV/EHU), 48940, Leioa, Spain.
Anal Chim Acta. 2022 May 29;1209:339837. doi: 10.1016/j.aca.2022.339837. Epub 2022 Apr 26.
The SuperCam instrument, onboard the Perseverance rover (Mars 2020 mission) is designed to perform remote analysis on the Martian surface employing several spectroscopic techniques such as Laser Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman (TRR), Time-Resolved Fluorescence (TRF) and Visible and Infrared (VISIR) reflectance. In addition, SuperCam also acquires high-resolution images using a color remote micro-imager (RMI) as well as sounds with its microphone. SuperCam has three main subsystems, the Mast Unit (MU) where the laser for chemical analysis and collection optics are housed, the Body Unit (BU) where the different spectrometers are located inside the rover, and the SuperCam Calibration Target (SCCT) located on the rover's deck to facilitate calibration tests at similar ambient conditions as the analyzed samples. To perform adequate calibrations on Mars, the 22 mineral samples included in the complex SCCT assembly must have a very homogeneous distribution of major and minor elements. The analysis and verification of such homogeneity for the 5-6 replicates of the samples included in the SCCT has been the aim of this work. To verify the physic-chemical homogeneity of the calibration targets, micro Energy Dispersive X-ray Fluorescence (EDXRF) imaging was first used on the whole surface of the targets, then the relative abundances of the detected elements were computed on 20 randomly distributed areas of 100 × 100 μm. For those targets showing a positive Raman response, micro-Raman spectroscopy imaging was performed on the whole surface of the targets at a resolution of 100 × 100 μm. The %RSD values (percent of relative standard deviation of mean values) for the major elements measured with EDXRF were compared with similar values obtained by two independent LIBS set-ups at spot sizes of 300 μm in diameter. The statistical analysis showed which elements were homogeneously distributed in the 22 mineral targets of the SCCT, providing their uncertainty values for further calibration. Moreover, nine of the 22 targets showed a good Raman response and their mineral distributions were also studied. Those targets can be also used for calibration purposes of the Raman part of SuperCam using the wavenumbers of their main Raman bands proposed in this work.
超级摄像机仪器，搭载在毅力号火星车（2020 年火星任务）上，旨在利用几种光谱技术对火星表面进行远程分析，例如激光诱导击穿光谱（LIBS）、时间分辨拉曼（TRR）、时间分辨荧光（TRF）和可见与红外（VISIR）反射率。此外，超级摄像机还使用彩色远程微型成像仪（RMI）获取高分辨率图像以及通过麦克风获取声音。超级摄像机有三个主要子系统，桅杆单元（MU），其中包含用于化学分析的激光和收集光学器件，车身单元（BU），其中位于火星车内部的不同光谱仪，以及超级摄像机校准目标（SCCT），位于火星车的甲板上，以在与分析样品相似的环境条件下进行校准测试。为了在火星上进行适当的校准，复杂的 SCCT 组件中包含的 22 个矿物样本必须具有主要和次要元素非常均匀的分布。这项工作旨在分析和验证 SCCT 中包含的样本的 5-6 个复制品的这种均匀性。为了验证校准目标的物理化学均匀性，首先对整个目标表面进行微能量色散 X 射线荧光（EDXRF）成像，然后在 20 个随机分布的 100×100 μm 区域上计算检测到的元素的相对丰度。对于显示出正拉曼响应的那些目标，在 100×100 μm 的分辨率下对整个目标表面进行微拉曼光谱成像。通过 EDXRF 测量的主要元素的 %RSD 值（平均值的相对标准偏差的百分比）与通过直径为 300 μm 的两个独立 LIBS 设备在点尺寸处获得的类似值进行了比较。统计分析显示了哪些元素在 SCCT 的 22 个矿物目标中均匀分布，为进一步校准提供了它们的不确定性值。此外，22 个目标中有 9 个显示出良好的拉曼响应，并且还研究了它们的矿物分布。这些目标也可以用于使用本工作中提出的主要拉曼带的波数来校准超级摄像机的拉曼部分。
