Eriksson Gustav, De Tullio Matteo, Carnovale Francesco, Inverardi Giovanni Novi, Morresi Tommaso, Houard Jonathan, Ropitaux Marc, Blum Ivan, Cadel Emmanuel, Lattanzi Gianluca, Thuvander Mattias, Andersson Martin, Hulander Mats, Taioli Simone, Vella Angela
Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Kemigården 4, 412 96 Gothenburg, Sweden.
Université Rouen Normandie, INSA Rouen Normandie, CNRS, GPM UMR 6634, F-76000 Rouen, France.
ACS Omega. 2025 Jul 22;10(30):33741-33754. doi: 10.1021/acsomega.5c04733. eCollection 2025 Aug 5.
Silicon dioxide is a suitable material to encapsulate proteins at room temperature so that they can be analyzed at the atomic level using laser-assisted atom probe tomography (La-APT). To achieve this goal, in this study we show that UV and deep-UV lasers can achieve a high success rate in La-APT of silica in terms of chemical resolution and three-dimensional image volume, with both lasers providing comparable results. Since the La-APT analyses are driven by photon absorption, in order to understand the mechanisms behind the enhanced absorption of UV light, we performed density functional theory calculations to model the electronic and optical properties of amorphous silica matrices generated using a Monte Carlo approach to structural optimization. In particular, we have investigated the role of various defects introduced during sample preparation, such as substitutional and interstitial carbon, sodium and gallium ions, and hydrogen. Our results show that the presence of defects increases the absorption of silica in the UV and deep-UV range and thus improves the La-APT capabilities of the material. However, due to the low density of free charge carriers resulting from the absorption of laser energy by defects, deviations from the nominal chemical composition and suboptimal chemical resolution may occur, potentially limiting the optimal acquisition of APT mass spectra.
二氧化硅是一种在室温下封装蛋白质的合适材料，这样就可以使用激光辅助原子探针断层扫描（La-APT）在原子水平上对其进行分析。为实现这一目标，在本研究中我们表明，就化学分辨率和三维图像体积而言，紫外激光和深紫外激光在二氧化硅的La-APT中可实现较高的成功率，两种激光给出的结果相当。由于La-APT分析是由光子吸收驱动的，为了理解紫外光增强吸收背后的机制，我们进行了密度泛函理论计算，以模拟使用蒙特卡罗结构优化方法生成的非晶二氧化硅基质的电子和光学性质。特别是，我们研究了样品制备过程中引入的各种缺陷的作用，如替代和间隙碳、钠和镓离子以及氢。我们的结果表明，缺陷的存在增加了二氧化硅在紫外和深紫外范围内的吸收，从而提高了材料的La-APT能力。然而，由于缺陷吸收激光能量导致自由电荷载流子密度较低，可能会出现与标称化学成分的偏差以及次优的化学分辨率，这可能会限制APT质谱的最佳采集。
