Recently, the latest issue of J Raman spectroscopy, the authoritative journal of Willey Raman spectroscopy, published the research results of the cooperation between Li Zhen, associate professor of Nanjing Agricultural University, Shao Xiaoqing (undergraduate), Wu Yiling (postgraduate) and he Kun, Ph.D. of China Petroleum Exploration and Development Research Institute, entitled:
“Tracking the fungus‐assisted biocorrosion of lead metal by Ramanimaging and scanning electron microscopy technique”。
In this study, the Raman electron microscope integrated system (rise) of Czech tescan company was used for the first time to trace the biological corrosion of fungi on lead metal.
By switching the electron beam signal and laser signal in the same area of the sample surface, the surface morphology information and Raman information of the sample are obtained respectively. For the first time in the world, the test of mineral / microbial samples by rise technology is realized, which makes up for the inadequacy of scanning electron microscopy and G single spectrum technology.
Rise Raman electron microscopy integrated system is a non-destructive detection technology.
The peak value in the spectrum was smoothed and normalized by this technique, and the secondary lead mineral with different morphology in this study was identified as lead oxalate by using the point analysis model. By analyzing the difference of Raman peak intensities between small (Fig. 3a) and large (Fig. 3b) lead Oxalate Particles at ~ 1440, ~ 1480 and ~ 1590 cm-1 in Fig. 3, it is determined that the orientations of secondary lead minerals are different (probably due to different growth stages).
At the same time, the Raman imaging using rise shows that the secondary minerals are more likely to form scales (FIG. 4A), and the mineral particles are well organized (rather than randomly distributed).
FIGURE 3 RISEspot analysis (0‐4500 cm‐1) on thesecondary Pb‐minerals with twodifferent morphologies.
A:The area occupied by the small particles; B: The area occupied by the largeparticles. The RISE spots were indicated by the circles under both SEM and LMmodes.
The six peaks were 498, 861, 902, 1447, 1483 and 1593 cm-1 for mapping.
According to rise analysis, in Raman mapping, the black area (not the point) may be caused by the ripple of the foil, but the image can clearly confirm the structure distribution of lead oxalate.
FIGURE4RISE analysis on the secondary Pb‐minerals with SEM and Raman mapping. A: Theimage of large particles ; B-G: The Raman mapping images in characterized peaksof Pb oxalate.
In this study, a variety of technologies are used to test the results, and it is found that:
(1) The morphology of the metal surface can be observed by SEM, and the chemical changes on the surface of the lead foil can be shown by the shift spectrum, but none of them can successfully determine the secondary mineral phase.
(2) The integrated Raman electron microscopy system of rise can meet these requirements at the same time. It has been proved that the secondary mineral is pbc2o4 and its distribution. At the same time, compared with the shift spectrum, the Raman spectrum can also effectively track the biomineralization process of lead.
Therefore, rise provides a powerful and effective method for the study of biological weathering on the surface of various materials!
In situ characterization of 1 + 1 & gt; 2
Orange lamp exploration and tescan provide advanced in-situ analysis and detection equipment, including the rise Raman electron microscope integrated system, tiam integrated mineral analysis system, electron microscope mass spectrometry fib-sem-tof-sims combined system, and high-resolution 4D in-situ CT rapid scanning system.
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