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arXiv 2605.01697cond-mat.mtrl-scicond-mat.soft
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物理约束学习金属有机框架中剂量依赖的光谱退化:基于原位低损耗EELS

Physics-Constrained Learning of Dose-Dependent Spectral Degradation in Metal--Organic Frameworks from In Situ Low-Loss EELS

Northwestern University(西北大学)

Gabriel T. dos Santos, Roberto dos Reis, Vinayak P. Dravid

AI总结:

本研究利用物理信息神经网络建模MIL-101(Fe)在电子束下的剂量依赖光谱退化,识别C--O和C--C为最敏感通道,并揭示π-π*窗口的混合响应,为MOF退化提供光谱约束描述。

摘要:

电子束辐照限制了束敏感杂化材料的原子级分辨率表征,然而将原位光谱与剂量依赖退化联系起来的定量模型仍然稀缺。在此,我们使用物理信息神经网络(PINN)对MIL-101(Fe)中由束诱导的光谱演化进行建模,数据来自原位低损耗电子能量损失谱(EELS)剂量序列。每个光谱被简化为固定窗口的低损耗描述符,$\tilde n_{\mathrm{eff},j}(\Phi)=\int_{\mathcal{W}_j}S(E,\Phi)\\,dE$,在标称的$\pi$--$\pi^{*}$、C--C、C--O和M--O窗口上评估。这些描述符是相对的窗口积分低损耗光谱面积,而非绝对的f-sum规则有效电子数。对于每个光谱通道,一个潜在完整性变量$C_i(\Phi)$在归一化剂量空间中遵循相同的非耦合幂律退化方程,$dC_i/d\phi=-k_i C_i^{p_i}$,并通过单调性、有界性和单一层次先验$k_{\mathrm{C\text{-}O}}\geq k_{\mathrm{C\text{-}C}}$进行正则化。应用于跨越152--1368~e$^-$/Å$^2$的九个剂量帧,集成PINN识别出C--O和C--C为对剂量最敏感的连接体相关通道,其半完整性阈值约为$1.0\times10^3$~e$^-$/Å$^2$。1--3~eV的$\pi$--$\pi^{*}$标记窗口随剂量增加而增大,因此被解释为混合低能响应,可能涉及振子强度重新分布而非单一键群的直接单调损失。该框架提供了对MOF退化的剂量依赖、光谱约束描述,同时也界定了固定窗口低损耗EELS在缺乏独立化学态验证时所能分配的限制。

英文摘要:

Electron-beam irradiation limits atomic-resolution characterization of beam-sensitive hybrid materials, yet quantitative models that connect \textit{in situ} spectroscopy to dose-dependent degradation remain scarce. Here we use a physics-informed neural network (PINN) to model beam-induced spectral evolution in MIL-101(Fe) from an in situ low-loss electron energy-loss spectroscopy (EELS) dose series. Each spectrum is reduced to fixed-window low-loss descriptors, $\tilde n_{\mathrm{eff},j}(Φ)=\int_{\mathcal{W}_j}S(E,Φ)\,dE$, evaluated over nominal $π$--$π^{*}$, C--C, C--O, and M--O windows. These descriptors are relative window-integrated low-loss spectral areas, not absolute f-sum-rule effective electron numbers. For each spectral channel, a latent integrity variable $C_i(Φ)$ obeys the same uncoupled power-law degradation equation in normalized dose space, $dC_i/dϕ=-k_i C_i^{p_i}$, regularized by monotonicity, boundedness, and a single hierarchy prior $k_{\mathrm{C\text{-}O}}\geq k_{\mathrm{C\text{-}C}}$. Applied to nine dose frames spanning 152--1368~e$^-$/Å$^2$, the ensemble PINN identifies C--O and C--C as the most strongly dose-sensitive linker-associated channels, with half-integrity thresholds of approximately $1.0\times10^3$~e$^-$/Å$^2$. The 1--3~eV $π$--$π^{*}$-labelled window increases with dose and is therefore interpreted as a mixed low-energy response, likely involving oscillator-strength redistribution rather than direct monotonic loss of a single bond population. The framework provides a dose-dependent, spectroscopy constrained description of MOF degradation while also defining the limits of what fixed-window low-loss EELS can assign without independent chemical-state validation.

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