A laser desorption postionization (LDPI) nanoscale resolution mass spectrometry imaging (MSI) technique based on a microlensed fiber is proposed for 3D imaging of microspheres which have a core–shell structure. Results show that the diameter of the sampling crater can be as small as 350 nm by introducing the desorption laser to the sample surface through the microlensed fiber. The use of laser postionization greatly solves the problem of weak signal caused by the very small sampling amount. A line scan of a sharp edge of Cr mesh shows that the imaging resolution of this method can reach to 300 nm. Through the imaging analysis of the alloy core–shell microspheres of Cr, Fe, Co, and Cu, the distribution of four elements at different positions can be observed visually. Particularly, the reconstruction 3D image of a single Nb–Zr core–shell particle demonstrates the potential of this technique in 3D imaging.

中文翻译：

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通过微透镜光纤激光解吸后电离质谱对核壳微球进行3D纳米化学成像。

提出了一种基于微透镜光纤的激光解吸后去离子化（LDPI）纳米级分辨率质谱成像（MSI）技术，用于具有核壳结构的微球的3D成像。结果表明，通过将解吸激光通过微透镜光纤引入样品表面，采样坑的直径可小至350 nm。激光去离子化的使用极大地解决了由于采样量很小而导致信号弱的问题。铬网的锋利边缘的线扫描显示该方法的成像分辨率可以达到300 nm。通过对Cr，Fe，Co和Cu合金核-壳微球的成像分析，可以直观地观察到四种元素在不同位置的分布。尤其，