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Abstract
The structures of retired components and potassium dihydrogen phosphate (KDP) crystal irradiated by high fluence are investigated using the combined methods of synchrotron radiation micro-X-ray fluorescence with micro-X ray diffraction. The distributions of potassium, phosphorus, iron, and copper exhibited an apparent centralization on the crater. The changes between phosphorus and potassium were the same in KDP crystal irradiated by high fluence but were different for retired components. The irradiation of KDP crystal by high fluence produced K2H2P2O7 and KPO3 crystals during laser-induced damage, but K2H2P2O7 and K2H8(PO4)2P2O7 crystals were produced for retired components. KDP crystal irradiated by high fluence was dehydrated completely but the retired components were incompletely decomposed.
© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
1. Introduction
Potassium dihydrogen phosphate (KDP) plays critical functions in large laser systems, such as the National Ignition Facility [1–3]. With the requirement of high-power laser output increase, the laser-induced damage (LID) of KDP crystals has attracted the attention of researchers. Nano-absorbing centers are usually regarded as precursors during LID [1,4,5]. Some precursors may be metal inclusions introduced during the process of KDP crystal growth [6–8]. The concentrated metal inclusions act as precursors that absorb energy because of their high absorption coefficient and thermal conductivity [9–11]. The metal inclusions absorb energy under high-power laser and become strong absorption sources once the temperature of precursors is higher than that of intrinsic bulk crystal. The surrounding materials begin to absorb energy and form damage craters at the end [12–15]. Pommiès et al. found that metal inclusions may play key roles in the LID by photo-thermal deflection and fluorescence spectroscopy [16]. However, the sensitivities of conventional methods are insufficient, and it is difficult to directly determine the relationship between the structural information and distribution of elements.
Synchrotron radiation techniques have become very popular with the development of high energy X-ray sources. In recent years, a variety of micro-analytical techniques have been applied in physics. The use of synchrotron micro-X-ray fluorescence (μ-XRF) microprobes is an effective technique to study the distribution of elements [17–21]. The advantages of μ-XRF are its non-destructive nature and ability to achieve high-resolution multi-elemental analysis. We can then obtain the distribution of elements on a microscopic scale [22]. However, each method has advantages and limitations. Synchrotron radiation complimentary techniques, such as micro-X-ray absorption spectroscopy and micro-X-ray diffraction (μ-XRD), have been widely used in the field of environmental science [23,24]. However, few studies have been reported regarding the application of synchrotron radiation complimentary techniques in LID research.
In this paper, we present some insight into the structural change of retired component and KDP crystal irradiated by high fluence. We explore the elements of interest and the structure of the damage sites by combining μ-XRF with μ-XRD. We employed μ-XRF to study the distribution of elements in the KDP crystal. The samples and experimental procedure are introduced in section 2. Using μ-XRF and μ-XRD, we present the structure of KDP crystal irradiated by high fluence and the retired component in section 3.1 and 3.2, respectively. We also used the complimentary techniques, namely μ-XRD, to obtain a complete understanding of the structure of damage sites. We then compared the results with other obtained by methods in section 3.3. The paper is summarized in section 4. The supplementary section are show at the end of the article. This work shows that the damage processes of KDP crystal vary between low and high fluence.
2. Samples and experimental procedure
The KDP crystals were grown by a conventional method and fabricated using single point diamond turning technology. The size of the KDP crystal irradiated by high fluence is 10 mm × 10 mm × 1 mm. The LID sites were generated on the front surface of the KDP crystal irradiated by a ~3 ω, 355-nm laser with a fluence of 11.54 J/cm2. The laser is linearly polarized. The temporal profile of the laser pulse is Gaussian, and its spot size is 0.22 mm2 on the sample plane. The pulse length (full width at half maximum, [FWHM]) and laser repetition rate are 6.8 ns and 1 Hz, respectively. The other part of the KDP sample comprises retired components. The size of the original sample is 300 mm × 300 mm × 10 mm and three 20 mm × 10 mm × 1 mm pieces from the original one are cut for experiments. The sample was subjected to 400 pulses of laser irradiation. The laser wavelength is 355 nm, and the FWHM is 1 ns. The average fluence is 1.2 J/cm2, and the peak of the fluence is 1.8 J/cm2. The typical surface morphology for the retired components is shown in Fig. 5(a). The sample and laser parameters are detailed in the literature [25].
Both μ-XRF and μ-XRF were carried out at the BL15U1 beam line of the Shanghai Synchrotron Radiation Facility (SSRF), China, which is a third–generation synchrotron radiation facility. The beam comes from the bending magnet source, and it is then monochromatized by a double-crystal Si (1, 1, 1) monochromator. The energy of the beam in the storage ring is 3.5 GeV. The light spot is focused from 2 μm to 100 μm by a pair of Kirpatrick–Baez mirrors (KB mirrors). The sample is placed on a movable XYZ table, and the precision of each axis is 0.1 μm. A Vortex 50-mm2 silicon drift detector is used to collect the μ-XRF signal, and the detector and the incident X-ray beam are placed at 90° geometry. This geometrical arrangement can significantly minimize the background that mainly results from the scattering of X-ray. The energy of the excitation radiation is monochromatized to 18 KeV (λ = 0.068 nm). We obtained potassium, iron, copper, and phosphorus under the excitation energy. The beam spot and the position of the sample are controlled by translation stages that combine beam-focusing microscopy with sample microscopy. The spot of the incident X-ray beam was focused to 5 μm in order to obtain an accurate result. The dwell time is set to 2 s for each pixel grid. A step size of 5 μm was chosen to obtain a continuous scanning result. We determined the scanning area using a laser confocal scanning microscope (LCMS) based on the actual morphology of damage. Two-dimensional (2-D) μ-XRD patterns are obtained on the position of the μ-XRF by using Mar165 CCD detector. The integration time at each pixel grid is set to 1 s. The images of diffraction rings are integrated and processed with the FIT2D program. We then obtained the resultant spectra (intensity versus 2θ), which are calibrated with the pattern of cerium dioxide.
3. Results and discussion
3.1 Structure of KDP crystal irradiated by high fluence
3.1.1 Damage craters along horizontal direction
Figure 1(a) shows a single damage crater on the surface of the KDP crystal irradiated by 11.54 J/cm2 using LCMS. The red origins on the scanning line do not represent actual points. The integration time is set to 20 s for each point in order to obtain clear fluorescence signals. We chose two scanning lines that are geometrically arranged at 90°. This method is suitable for statistical results. We scanned a line along the horizontal direction, as shown in Fig. 1(a). Figure 1(b) shows the distributions of potassium, phosphorus, iron, and copper for the crater shown in Fig. 1(a). The fluorescence yield and detection are related to the atomic number and fluorescence energy. Thus, the scale of the left counts is only used for comparison between the same elements in Fig. 1(b). We can see that the distributions of potassium, phosphorus, and iron exhibit an apparent centralization in the damage crater. The metal inclusions concentrate at some positions in the range from a1 to d10. Thus, the distribution of elements shows some relationship with the damage sites.
Fig. 1 Position of scanning line for horizontal direction (a) and distribution of different elements (b) along the horizontal direction on the surface of sample irradiated by 11.54 J/cm2.
Fig. 2 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7, and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7, and KPO3 crystals, respectively.
Figure 2 shows the diffraction patterns measured at the position of μ-XRF along the horizontal direction. It is only the most representative scattering pattern, and the rest are as shown in Fig. 9 in the Appendix, which is the same as below. Miller indices are used to specify planes in crystals. Please see Figs. 10-17 in the Appendix for whole scattering patterns and the results about the repeatability of the experiments. The number of indices matches the dimensions of the crystal. Although the peaks overlap in the μ-XRD, the matching of the integrated diffraction patterns was successful. The diffraction patterns are mainly assigned to polycrystalline KDP, K2H2P2O7, and KPO3 crystals. The polycrystalline KDP runs through the horizontal direction. The K2H2P2O7 and KPO3 crystals result from KDP dehydration products under laser irradiation. Negres et al. [26] showed a KPO3 crystal at LID sites on the surface by Raman and O K-edge XANES spectra. The range from a1 to d10 corresponds to the positions of a1…a10…b1…b10…c1…c10…d1… d10 in Fig. 2. From Fig. 2, we find that the intensities of the diffraction peaks vary. For instance, the diffraction peaks of (3-10) plane for the K2H2P2O7 crystal are very high from a1 to b9, but become low at b10. The diffraction peaks then increase from c5 to c10 and subsequently decrease from d1. The (421) plane of the KPO3 crystal increases from a3 to b6. The diffraction peaks of (532) plane for the KPO3 crystal decrease from b6 to b10. The positions of dehydration products correspond to the range from a1 to d10 in the μ-XRF, and in the damage crater along the horizontal direction. Outside of the range, the diffraction patterns are similar to that of a1 (not shown). The peak heights of relevant reflections as a function of the position across the crater are present in the supplementary material, and consistent with the elemental analysis shown in Fig. 1(b). The diffraction peaks increase with the content of phase in damage crater.
3.1.2 Damage craters along vertical direction
The distributions of potassium, phosphorus, iron, and copper show the same trend. In contrast to the distribution of the copper, the potassium, phosphorus, and iron show much more refined changes.
Figure 4 shows the diffraction patterns measured at the position of μ-XRF along the vertical direction. We also find the polycrystalline KDP, K2H2P2O7 crystal, and KPO3 crystal in the crater. The polycrystalline KDP occurs along the vertical direction. However, the dehydration products for the KPO3 crystal correspond to the range from A1 to E10 in the μ-XRF and in Fig. 3(b) along the vertical direction. Likewise, the intensities of the diffraction peak vary at different points. In comparison with μ-XRF along the vertical direction, the diffraction peaks are strong where the elements are concentrated. Based on the results above, we believe that thermal dehydration products appear on the damage pit. The KDP crystal decomposes into K2H2P2O7 and KPO3 crystals by losing water. The process can be described as follows:
The total thermal decomposition process occurs as follows:After combining μ-XRF with μ-XRD, we find that the distribution of elements concentrate increases with dehydration products. The distributions of elements correspond to the change of the structure.Fig. 3 Position of scanning line for vertical direction (a) and the distribution of different elements (b) along the vertical direction on the surface of sample. Figure 3(a) shows the distribution of different elements for the crater along the vertical direction.
Fig. 4 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7 and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7, and KPO3 crystals, respectively.
3.2 Structure of retired component
3.2.1 Damage craters along horizontal direction
Fig. 5 Position of scanning line for horizontal direction (a) and the distribution of different elements (b) along the horizontal direction on the surface of retired component. Figure 5(b) shows the distributions of different elements for the crater along the horizontal direction. The distributions of potassium and phosphorus show different trends, so the atomic proportions of potassium and phosphorus in retired components are different. The element distributions of retired component show a distinct change from KDP crystals irradiated by high fluence.
Figure 6 shows the diffraction patterns measured at the position of the μ-XRF along the horizontal direction. We found polycrystalline KDP, K2H8(PO4)2P2O7, and K2H2P2O7 crystals in the crater, which occur along the horizontal direction. The intensities of diffraction peaks show a slight change. The atomic proportions of potassium and phosphorus in KDP and K2H2P2O7 crystal are the same, but are different in the K2H8(PO4)2P2O7 crystal, and the reason for this is because of the different trends in the distributions of potassium and phosphorus in the μ-XRF.
Fig. 6 Integrated μ-XRD pattern matching the point of the μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent polycrystalline KDP, K2H2P2O7 and K2H8(PO4)2P2O7 crystals, respectively. The black, magenta, and blue Miller indices represent diffractive planes of KDP, K2H2P2O7, and K2H8(PO4)2P2O7 crystals, respectively.
3.2.2 Damage craters along vertical direction
Fig. 7 Position of scanning line for vertical direction (a) and the distribution of different elements (b) along the vertical direction on the surface of retired components. Figure 7(b) shows the distribution of different elements for the crater along the vertical direction. In contrast with KDP crystals irradiated by a fluence of 11.54 J/cm2, the distributions of elements in the retired sample slightly changes. The distribution of potassium is uniform, and metal inclusions are dispersed randomly in the undamaged KDP crystal. Phase transitions or degradations occur in the KDP crystal when the distribution of potassium changes. When the crystal is irradiated, the metal inclusions act as precursors to absorb laser energy. The temperature of the metal inclusions can be high and produce high pressure under high fluence. The crystal will immediately decompose, and materials with metal inclusions are subsequently ejected. Thus, the distributions of elements exhibit significant changes for KDP crystal irradiated by fluence of 11.54 J/cm2. The fluence for retired samples is low, and thus changes slightly.
Figure 8 shows the diffraction patterns measured at the position of the μ-XRF along the vertical direction. We found the polycrystalline KDP, K2H8(PO4)2P2O7, and K2H2P2O7 crystal in the crater, which occur along the vertical direction. Based on the above analysis, the K2H8(PO4)2P2O7 and K2H2P2O7 crystals occur during the process of thermal dehydration. The P-O bond fracture and the crystal lose –OH groups during the process of formation of K2H2P2O7, and it can be described as follows:
The structure of the K2H8(PO4)2P2O7 crystal is K2[H2PO4—H—H2P2O7—H—H2PO4]. From the structure, we can see that one H2P2O7 group connects two H2PO4 groups. Then, it forms a compound that has a long chain. The result is consistent with our previous work [25]. The fluences for retired samples are low and undergo 400 pulses. The crystals break down and are incompletely decomposed into H2P2O7 groups. While the KPO3 crystals appear in KDP crystals under high fluence, the KDP crystal is in total breakdown. The results show that the damage processes of KDP crystals vary between low and high fluence.Fig. 8 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent polycrystalline KDP, K2H2P2O7, and K2H8(PO4)2P2O7 crystals, respectively. The black, magenta, and blue Miller indices represent diffractive planes of KDP, K2H2P2O7, and K2H8(PO4)2P2O7 crystals, respectively.
3.3 Comparison with other methods
The scanning electron microscope can show the damage morphology clearly, but it cannot’ depict information about the structure. The laser damage of 3 ω is related to the iron concentration by photo-thermal deflection [16]. However, the relationship between the LID process and damage sites cannot be shown.
In the present study, the distributions and crystalline phases are investigated by a combination of μ-XRF and μ-XRD. This method can prevent chemical destruction. The method provides a novel insight into the process of LID on a micro-scale, and simultaneously acquires the μ-XRD patterns, which provide accurate information about the crystal phases. Most importantly, the micro-analytical results presented in this paper clearly indicate the relationship between the distribution of thermal decomposed products and damage sites on the whole crater.
4. Conclusion
The distribution of metal inclusions and the structural changes of the KDP crystal irradiated by ultraviolet laser pulses were investigated using synchrotron μ-XRF and μ-XRD. The metal inclusions correlate well with the damage process from μ-XRF. We obtained the μ-XRD pattern, which simultaneously provided accurate information about the crystalline phase. The KDP crystal under high fluence shows K2H2P2O7 and KPO3 crystals during LID. However, the crystal incompletely decomposed into K2H2P2O7 and K2H8(PO4)2P2O7 crystals for retired components. Both μ-XRF and μ-XRD were performed simultaneously, and the results show that the damage processes of the KDP crystal vary between low and high fluence. We provide evidence about the relationship between metal inclusions and phase transition during LID directly. The proposed method is effective in studying the mechanism of LID in KDP.
Appendix
5. Structure of KDP crystal irradiated by high fluence
5.1. Damage craters along horizontal direction
Fig. 9 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7 and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7 and KPO3 crystals, respectively. They show the diffraction patterns measured at the position of μ-XRF along the horizontal direction. The range from a1 to d10 corresponds to the position of a1…d10 in Fig. 1(b) in the main text.
Fig. 10 This is the peak heights of relevant reflections as a function of position across the crater, and consistent with the elemental analysis shown in Fig. 1(b), Fig. 3, main text, respectively.
5.2 Damage craters along vertical direction
Fig. 11 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7 and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7 and KPO3 crystals, respectively. They show the diffraction patterns measured at the position of μ-XRF along the vertical direction. The range from A1 to E10 corresponds to the position of A… E10 in Fig. 3(b) in the main text
6 Structure of retired component
6.1 Damage craters along horizontal direction
Fig. 12 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent polycrystalline KDP, K2H2P2O7, and K2H8(PO4)2P2O7 crystal, respectively. The black, magenta, and blue Miller indices represent diffractive planes of KDP, K2H2P2O7, and K2H8(PO4)2P2O7 crystals, respectively.
6.2 Damage craters along vertical direction
Fig. 13 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent polycrystalline KDP, K2H2P2O7 and K2H8(PO4)2P2O7 crystals, respectively. The black, magenta, and blue Miller indices represent diffractive planes of KDP, K2H2P2O7 and K2H8(PO4)2P2O7 crystals, respectively.
7 The results about the repeatability of the experiments
7.1. Damage craters along horizontal direction
Fig. 14 Position of scanning line for horizontal direction (a) and the distribution of different elements (b) along the horizontal direction on the surface of sample.
Fig. 15 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7 and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7 and KPO3 crystals, respectively. They show some diffraction patterns measured at the position of μ-XRF along the horizontal direction.
7.2 Damage craters along vertical direction
Fig. 16 Position of scanning line for vertical direction (a) and the distribution of different elements (b) along the vertical direction on the surface of sample.
Fig. 17 Integrated μ-XRD pattern matching the point of μ-XRF and the attribution of diffraction peaks. The star, square, and triangle represent KDP, K2H2P2O7 and KPO3 crystals, respectively. The black, magenta, and red Miller indices represent diffractive planes of KDP, K2H2P2O7 and KPO3 crystals, respectively. They show some diffraction patterns measured at the position of μ-XRF along the vertical direction.
Funding
National Natural Science Foundation of China under Grant (NSFC) (51402173); Fundamental Research Funds for the central universities (FRF-TP-15-099A1).
Acknowledgments
We acknowledge Lisong Zhang and Dongting Cai for their help during the samples preparation and Dr. Lili Zhang at the SSRF for their support during data collection.
References
1. C. W. Carr, H. B. Radousky, and S. G. Demos, “Wavelength dependence of laser-induced damage: determining the damage initiation mechanisms,” Phys. Rev. Lett. 91(12), 127402 (2003). [CrossRef] [PubMed]
2. K. Boopathi, P. Rajesh, P. Ramasamy, and P. Manyum, “Comparative studies of glycine added potassium dihydrogen phosphate single crystals grown by conventional and Sankaranaryanan–Ramasamy methods,” Opt. Mater. 35(5), 954–961 (2013). [CrossRef]
3. J. J. De Yoreo, A. K. Burnham, and P. K. Whitman, “Developing KH2PO4 and KD2PO4 crystals for the world’s most power laser,” Int. Mater. Rev. 47(3), 113–152 (2002). [CrossRef]
4. F. DeMange, R. A. Negres, N. P. Zaitseva, H. B. Radousky, and S. G. Demos, “Correlation of laser-induced damage performance to crystal growth conditions in KDP and DKDP crystals,” in Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, CLEO/QELS 2006 (2006). [CrossRef]
5. Z. Y.-A. H. U. Guo-Hang and S. U. N. Shao-Tao, “Growth characteristics and mechanism of surface and bulk damage in KDP and DKDP crystals,” Chin. Phys. Lett. 26(8), 087805 (2009). [CrossRef]
6. D. C. Guo, X. D. Jiang, J. Huang, F. R. Wang, H. J. Liu, X. Xiang, G. X. Yang, W. G. Zheng, and X. T. Zu, “Effects of γ-ray irradiation on optical absorption and laser damage performance of KDP crystals containing arsenic impurities,” Opt. Express 22(23), 29020–29030 (2014). [CrossRef] [PubMed]
7. K. T. S. N. Y. Garces and L. E. Halliburton, “Optical absorption and electron paramagnetic resonance of Feions in KDP crystals,” J. Cryst. Growth 225(2–4), 435–439 (2001). [CrossRef]
8. C. M. R. Remédios, W. Paraguassu, G. D. Saraiva, D. P. Pereira, P. C. de Oliveira, P. T. C. Freire, J. Mendes-Filho, F. E. A. Melo, and A. O. dos Santos, “Temperature-dependent Raman scattering of KDP:Mn (0.9% weight of Mn) crystal,” J. Raman Spectrosc. 41(5), 1318–1322 (2010). [CrossRef]
9. P. DeMange, C. W. Carr, R. A. Negres, H. B. Radousky, and S. G. Demos, “Laser annealing characteristics of multiple bulk defect populations within DKDP crystals,” J. Appl. Phys. 104(10), 103103 (2008). [CrossRef]
10. K. Wang, C. Fang, J. Zhang, X. Sun, S. Wang, Q. Gu, X. Zhao, and B. Wang, “Laser-induced damage mechanisms and improvement of optical qualities of bulk potassium dihydrogen phosphate crystals,” J. Cryst. Growth 287(2), 478–482 (2006). [CrossRef]
11. P. Demange, R. A. Negres, C. W. Carr, H. B. Radousky, and S. G. Demos, “Laser-induced defect reactions governing damage initiation in DKDP crystals,” Opt. Express 14(12), 5313–5328 (2006). [CrossRef] [PubMed]
12. M. F. Koldunov and A. A. Manenkov, “Theory of laser-induced inclusion-initiated damage in optical materials,” Opt. Eng. 51(12), 121811 (2012). [CrossRef]
13. J. Shao, A. A. Manenkov, T. Jitsuno, and W. Rudolph, “Fundamental mechanisms of laser-induced damage in optical materials: today's state of understanding and problems,” Proc. SPIE 8786, 878611 (2013).
14. B. Ma, Y. Zhang, H. Ma, H. Jiao, X. Cheng, and Z. Wang, “Influence of incidence angle and polarization state on the damage site characteristics of fused silica,” Appl. Opt. 53(4), A96–A102 (2014). [CrossRef] [PubMed]
15. C. W. Carr, H. B. Radousky, A. M. Rubenchik, M. D. Feit, and S. G. Demos, “Localized dynamics during laser-induced damage in optical materials,” Phys. Rev. Lett. 92(8), 087401 (2004). [CrossRef] [PubMed]
16. M. Pommiès, D. Damiani, X. Le Borgne, C. Dujardin, A. Surmin, J. C. Birolleau, F. Pilon, B. Bertussi, and H. Piombini, “Impurities detection by optical techniques in KH2PO4 crystals,” Opt. Commun. 275(2), 372–378 (2007). [CrossRef]
17. R. Alberti, C. Fiorini, C. Guazzoni, T. Klatka, and A. Longoni, “Elemental mapping by means of an ultra-fast XRF spectrometer based on a novel high-performance monolithic array of silicon drift detectors,” Nucl. Instrum. Meth. A 580(2), 1004–1007 (2007). [CrossRef]
18. M. S. J. M. Chatterjee and S. Roy, “Determination of heavy metals in industrial wastes by SXRF method,” Radiat. Phys. Chem. 64(5-6), 369–372 (2002). [CrossRef]
19. M. F. Guerra, M. Radtke, I. Reiche, H. Riesemeier, and E. Strub, “Analysis of trace elements in gold alloys by SR-XRF at high energy at the BAMline,” Nucl. Instrum. Meth. B 266(10), 2334–2338 (2008). [CrossRef]
20. M. J. Farquharson, K. Geraki, G. Falkenberg, R. Leek, and A. Harris, “The localisation and micro-mapping of copper and other trace elements in breast tumours using a synchrotron micro-XRF system,” Appl. Radiat. Isot. 65(2), 183–188 (2007). [CrossRef] [PubMed]
21. K. Geraki, M. J. Farquharson, D. A. Bradley, and R. P. Hugtenburg, “A synchrotron XRF study on trace elements and potassium in breast tissue,” Nucl. Instrum. Meth. B 213, 564–568 (2004). [CrossRef]
22. L. Vincze, B. Vekemans, F. E. Brenker, G. Falkenberg, K. Rickers, A. Somogyi, M. Kersten, and F. Adams, “Three-dimensional trace element analysis by confocal X-ray microfluorescence imaging,” Anal. Chem. 76(22), 6786–6791 (2004). [CrossRef] [PubMed]
23. E. Nakazawa, T. Ikemoto, A. Hokura, Y. Terada, T. Kunito, S. Tanabe, and I. Nakai, “The presence of mercury selenide in various tissues of the striped dolphin: evidence from mu-XRF-XRD and XAFS analyses,” Metallomics: Integrated Biometal Science 3, 719–725 (2011).
24. Y. M. Zhu, H. Zhang, S. S. Fan, S. J. Wang, Y. Xia, L. M. Shao, and P. J. He, “In-situ determination of metallic variation and multi-association in single particles by combining synchrotron microprobe, sequential chemical extraction and multivariate statistical analysis,” J. Hazard. Mater. 276, 241–252 (2014). [CrossRef] [PubMed]
25. X. Li, B. Liu, C. Yan, C. Liu, and X. Ju, “Investigating the surface electronic structures of retired components and irradiated KDP crystals with different fluences by XANES spectroscopy,” Opt. Mater. Express 8(4), 816–823 (2018). [CrossRef]
26. R. A. Negres, S. O. Kucheyev, P. DeMange, C. Bostedt, T. van Buuren, A. J. Nelson, and S. G. Demos, “Decomposition of KH2PO4 crystals during laser-induced breakdown,” Appl. Phys. Lett. 86(17), 171107 (2005). [CrossRef]
