Efficiency of the formation of acid-resistant Calcium-oxalate layers on limestone

Scientific background: Carbonate-based stone monuments and buildings are susceptible to weathering in acidic environments. To combat surface corrosion and slow down material deterioration, protective coatings that inhibit calcite dissolution have been proposed. The efficiency and integrity of the coatings was studied by measuring sulfur distribution along the treated surface. Such experiment cannot be efficiently performed with standard SSD PIXE detectors due to high overlap between the strong Ca K x-ray escape peaks and S Kα. For that purpose, a new parallel-beam wavelength dispersive (PB-WDS) X-ray emission spectrometer at JSI have been used which achieves high energy resolution in the eV range and is able to measure S distribution on the surface of treated marble samples. Measurements performed within TNA project: The new PB-WDS X-ray emission spectrometer at J. Stefan Institute (Ljubljana, Slovenia) was used to map the presence of Sulphur on the surface of 13 marble samples treated with different coatings and after exposure to 2% sulfuric acid. Ge(111) crystal analyzer was used in the spectrometer to record the S Ka signal, the overall scan size was 5 × 5 mm2. Data files: We are sharing the files produced during measurements. The signal from the detector preamplifier was processed with the XIA DXP-XMAP digital pulse processor. The files are two main formats: Files containing mapping data. The spectrometer was set to the Bragg angle corresponding to the energy of the S Ka emission line. In a .zip folder, with 4 .mca files for every measured point (extension: _0-Si(Li) detector, _2- PB-WDS spectrometer) High energy resolution spectra recorded at selected points on the sample surface. # Filename 1 VES_A1_5.zip Map of S on VES_A1_5 sample. Ge 111, 100X100 points, 50μm step, 4s/point 2 S_X80_Y85.zip Scan over S Ka and Kb peak on the surface of VES_A1_5 sample. Point position x = 80px, y = 85px 3 VES_A3_5.zip Map of S on VES_A3_5 sample. Ge 111, 100X100 points, 50μm step, 4s/point 4 S_X95_Y33.zip Scan over S Ka and Kb peak on the surface of VES_A3_5 sample. Point position x = 95px, y = 33px 5 VES_A1_12.zip Map of S on VES_A1_12 sample. Ge 111, 40x40 points, 125μm step, 5s/point 6 S_X3_Y3.zip Scan over S Ka and Kb peak on the surface of VES_A1_12 sample. Point position x = 3px, y = 3px. Z position optimized to maximum at this point 7 S_X20_Y20.zip Scan over S Ka and Kb peak on the surface of VES_A1_12 sample. Point position x = 20px, y = 20px. Z position optimized to maximum at this point 8 S_X35_Y20.zip Scan over S Ka and Kb peak on the surface of VES_A1_12 sample. Point position x = 35px, y = 20px. Z position optimized to maximum at this point 9 CAR_A1_12.zip Map of S on VES_A1_12 sample. Ge 111, 80x80 points, 65μm step, 4s/point 10 CAR_A1_12_back_side.txt Scan over S Ka and Kb peak on the back surface of CAR_A1_12 sample. 11 VES_A1_12_Washed.zip Sample washed under running water. 2250 eV - 2350 eV; stepsize = 1.00eV; 6s/point or 10s/point for back 12 VES_A2_12.zip Line map of S on VES_A2_12. 10x1 points, 1mm stepsize, 10s/point 13 CAR_A3_5.zip Line map of S on CAR_A3_5. 10x1 points, 1mm stepsize, 10s/point 14 CAR_A1_5.zip Line map of S on CAR_A1_5. 10x1 points, 1mm stepsize, 10s/point1 15 VES_A3_12.zip Line map of S on VES_A3_12. 10x1 points, 1mm stepsize, 10s/point + Map of S on VES_A3_12 sample. Ge 111, 50x25 points, 200μm step, 3s/point 16 VES_A2_5.zip Line map of S on VES_A2_5. 5x1 points, 1mm stepsize, 10s/point 17 CAR_A2_5.zip Line map of S on CAR_A2_5. 5x1 points, 1mm stepsize, 10s/point 18 CAR_A2_12.zip Line map of S on CAR_A2_12. 5x1 points, 1mm stepsize, 10s/point 19 CAR_A3_12.zip Line map of S on CAR_A3_12. 5x1 points, 1mm stepsize, 10s/point科学背景 碳酸盐基石质文物与建筑在酸性环境中易发生风化劣化。为抑制表面腐蚀、延缓材料降解，研究者提出了可阻断方解石溶解的防护涂层方案。为评估此类涂层的防护效率与结构完整性，需沿处理后的样品表面测定硫元素的分布情况。但由于强Ca K X射线逃逸峰与S Kα峰存在严重谱峰重叠，标准SSD PIXE探测器（SSD PIXE detector）无法高效完成此类测量实验。为此，斯洛文尼亚约瑟夫·斯特凡研究所（JSI）搭建了一套新型平行束波长色散（parallel-beam wavelength dispersive, PB-WDS）X射线发射光谱仪，该设备可实现电子伏特（eV）量级的高能量分辨率，能够精准测量经涂层处理的大理石样品表面的硫分布。 TNA项目实验内容 本实验依托TNA计划开展：位于斯洛文尼亚卢布尔雅那的约瑟夫·斯特凡研究所（J. Stefan Institute）的新型PB-WDS X射线发射光谱仪，被用于对13块经不同涂层处理并暴露于2%硫酸环境后的大理石样品表面的硫分布进行测绘。光谱仪采用Ge(111)晶体分析仪记录S Kα信号，整体扫描尺寸为5 × 5 mm²。 数据文件说明 本次共享的文件均为实验测量过程中产生的原始数据。探测器前置放大器输出的信号经XIA DXP-XMAP数字脉冲处理器完成预处理。文件主要分为两类： 1. 测绘数据文件：光谱仪被设置在对应S Kα发射线能量的布拉格角位置。相关数据打包于.zip压缩包中，每个测量点位对应4个.mca格式文件（命名后缀说明：_0代表Si(Li)探测器（Si(Li) detector），_2代表PB-WDS光谱仪）。 2. 定点高分辨谱线数据：在样品表面选定点位采集的高能量分辨率X射线谱线数据。 文件名及对应数据说明 1. VES_A1_5.zip：VES_A1_5样品表面硫分布测绘图。采用Ge(111)晶体分析仪，扫描点数为100×100，步长50μm，每点采集时长4s 2. S_X80_Y85.zip：VES_A1_5样品表面S Kα与S Kβ峰扫描谱数据。采样点位坐标x=80像素（pixel, px），y=85像素 3. VES_A3_5.zip：VES_A3_5样品表面硫分布测绘图。采用Ge(111)晶体分析仪，扫描点数为100×100，步长50μm，每点采集时长4s 4. S_X95_Y33.zip：VES_A3_5样品表面S Kα与S Kβ峰扫描谱数据。采样点位坐标x=95像素，y=33像素 5. VES_A1_12.zip：VES_A1_12样品表面硫分布测绘图。采用Ge(111)晶体分析仪，扫描点数为40×40，步长125μm，每点采集时长5s 6. S_X3_Y3.zip：VES_A1_12样品表面S Kα与S Kβ峰扫描谱数据。采样点位坐标x=3像素，y=3像素，该点位Z轴位置已优化至信号峰值处 7. S_X20_Y20.zip：VES_A1_12样品表面S Kα与S Kβ峰扫描谱数据。采样点位坐标x=20像素，y=20像素，该点位Z轴位置已优化至信号峰值处 8. S_X35_Y20.zip：VES_A1_12样品表面S Kα与S Kβ峰扫描谱数据。采样点位坐标x=35像素，y=20像素，该点位Z轴位置已优化至信号峰值处 9. CAR_A1_12.zip：CAR_A1_12样品表面硫分布测绘图。采用Ge(111)晶体分析仪，扫描点数为80×80，步长65μm，每点采集时长4s 10. CAR_A1_12_back_side.txt：CAR_A1_12样品背面表面S Kα与S Kβ峰扫描谱数据 11. VES_A1_12_Washed.zip：经流水冲洗处理的VES_A1_12样品数据。采集能区为2250 eV - 2350 eV，能量步长1.00 eV；正面样品每点采集时长6s，背面样品每点采集时长10s 12. VES_A2_12.zip：VES_A2_12样品表面硫分布线扫描图。扫描点数为10×1，步长1mm，每点采集时长10s 13. CAR_A3_5.zip：CAR_A3_5样品表面硫分布线扫描图。扫描点数为10×1，步长1mm，每点采集时长10s 14. CAR_A1_5.zip：CAR_A1_5样品表面硫分布线扫描图。扫描点数为10×1，步长1mm，每点采集时长10s 15. VES_A3_12.zip：包含两组数据：①VES_A3_12样品表面硫分布线扫描图，扫描点数为10×1，步长1mm，每点采集时长10s；②VES_A3_12样品表面硫分布测绘图，采用Ge(111)晶体分析仪，扫描点数为50×25，步长200μm，每点采集时长3s 16. VES_A2_5.zip：VES_A2_5样品表面硫分布线扫描图。扫描点数为5×1，步长1mm，每点采集时长10s 17. CAR_A2_5.zip：CAR_A2_5样品表面硫分布线扫描图。扫描点数为5×1，步长1mm，每点采集时长10s 18. CAR_A2_12.zip：CAR_A2_12样品表面硫分布线扫描图。扫描点数为5×1，步长1mm，每点采集时长10s 19. CAR_A3_12.zip：CAR_A3_12样品表面硫分布线扫描图。扫描点数为5×1，步长1mm，每点采集时长10s