<br>通过红外光谱和量子化学模型的相互作用揭示 HCN 和宇宙硅酸盐之间的界面化学,The Journal of Physical Chemistry C

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通过红外光谱和量子化学模型的相互作用揭示 HCN 和宇宙硅酸盐之间的界面化学
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2024-08-20 , DOI: 10.1021/acs.jpcc.4c03454
Niccolò Bancone _{1,

2} , Rosangela Santalucia ₂ , Stefano Pantaleone ₂ , Piero Ugliengo ₂ , Lorenzo Mino ₂ , Albert Rimola ₁ , Marta Corno

Affiliation

了解氰化氢 (HCN) 和硅酸盐表面之间的相互作用对于阐明星际颗粒核心以及彗星和陨石基质中发生的生命起源过程至关重要。在本研究中，我们通过将低温（100–150 K）下的实验红外光谱与周期性 DFT 模拟相结合，表征了 HCN 在结晶镁橄榄石（Mg ₂ SiO ₄ ）（最丰富的宇宙硅酸盐之一）表面上的吸附特征。结果表明，分子和解离 HCN 吸附络合物作为所考虑的镁橄榄石晶面的函数共存。分子吸附在最稳定的表面上占主导地位，而解离吸附主要发生在稳定性较低的表面上，由表面暴露的 Mg ²⁺ -O ^2-离子对增强的路易斯酸碱行为催化。对整组吸附情况进行了谐波频率计算，并与实验红外波段进行了比较。为了理清对实验宽带产生影响的每种振动模式，我们在预测的频率集和实验频带之间进行了最佳非线性拟合。该过程的结果使我们能够（i）通过将计算的简正振动模式分配给每个谱带的主要特征来对实验红外光谱进行解卷积，以及（ii）揭示哪些晶面对吸附物振动谱带的贡献最大，提供有关样品形态的信息。目前的简单程序非常通用，并且在复杂无机材料表面吸附物红外光谱的精细表征中具有广泛的意义。

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Unraveling the Interface Chemistry between HCN and Cosmic Silicates by the Interplay of Infrared Spectroscopy and Quantum Chemical Modeling

Understanding the interaction between hydrogen cyanide (HCN) and silicate surfaces is crucial for elucidating the prebiotic processes occurring on interstellar grain cores as well as in cometary and meteoritic matrices. In this study, we characterized the adsorption features of HCN on crystalline forsterite (Mg₂SiO₄) surfaces, one of the most abundant cosmic silicates, by combining experimental infrared spectra at low temperatures (100–150 K) with periodic DFT simulations. Results showed the coexistence of both molecular and dissociative HCN adsorption complexes as a function of the considered forsterite crystalline face. Molecular adsorptions dominate on the most stable surfaces, while dissociative adsorptions occur predominantly on surfaces of lower stability, catalyzed by the enhanced Lewis acid–base behavior of surface-exposed Mg²⁺–O^2– ion pairs. On the whole set of adsorption cases, harmonic frequency calculations were carried out and compared with the experimental infrared bands. To disentangle each vibrational mode contributing to the experimental broad bands, we run the best nonlinear fit between the predicted set of frequencies and the experimental bands. The outcome of this procedure allowed us to (i) deconvolute the experimental IR spectrum by assigning computed normal modes of vibrations to the main features of each band and (ii) reveal which crystal faces are responsible for the largest contribution to the adsorbate vibrational bands, giving information about the morphology of the samples. The present straightforward procedure is quite general and of broad interest in the fine characterization of the infrared spectra of adsorbates on complex inorganic material surfaces.

更新日期：2024-08-20

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