H2 在 Ag 和 Au 纳米粒子上的光解离：尺寸和等离激元与带间跃迁对离解阈值强度的影响,The Journal of Physical Chemistry C

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H2 在 Ag 和 Au 纳米粒子上的光解离：尺寸和等离激元与带间跃迁对离解阈值强度的影响
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-02-15 , DOI: 10.1021/acs.jpcc.3c00006
Sajal Kumar Giri ₁ , George C. Schatz ₁

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本文提供了有关使用基于紧束缚电子结构代码 DFTB+ 的实时 TDDFT 模拟等离子体驱动化学反应的新见解，以及对 H 2 离解的_应用在具有 19-489 个原子的八面体银和金纳米粒子上。这些计算的一个新组成部分涉及对 300 K 规范集合进行采样以确定计算可能结果的分布，并且通过这种方法，我们能够确定解离阈值作为激光强度、波长和纳米团簇大小的函数。我们表明阈值强度随纳米团簇大小的倒数幂而变化，这使得可以将结果外推到更典型的实验研究的大小。从该外推法获得的强度大约是脉冲实验中使用的以上功率的 100 倍。与之前的实时模拟相比，这是对理论和实验的更接近的比较，其余的差异可以根据与星团形成相关的电磁热点来理解。我们还比较了等离激元激发与带间激发对反应阈值的影响，表明对于银团簇，等离子激元激发导致较低的阈值，但对于金团簇，带间激发更有效。我们的研究还包括对进出 H 的电荷转移的分析₂分子，以及脉冲期间和之后的轨道布居数测定，显示了金属激发与 H ₂反键能级位置之间的相关性。

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Photodissociation of H2 on Ag and Au Nanoparticles: Effect of Size and Plasmon versus Interband Transitions on Threshold Intensities for Dissociation

This Article provides new insights concerning the simulation of plasmon-driven chemical reactions using real-time TDDFT based on the tight-binding electronic structure code DFTB+, with applications to the dissociation of H₂ on octahedral silver and gold nanoparticles with 19–489 atoms. A new component of these calculations involves sampling a 300 K canonical ensemble to determine the distribution of possible outcomes of the calculations, and with this approach we are able to determine the threshold for dissociation as a function of laser intensity, wavelength, and nanocluster size. We show that the threshold intensity varies as an inverse power of nanocluster size, which makes it possible to extrapolate the results to sizes that are more typical of experimental studies. The intensities obtained from this extrapolation are around a factor of 100 above powers used in the pulsed experiments. This is a closer comparison of theory and experiment than has been obtained in previous real-time simulations, and the remaining discrepancy can be understood in terms of electromagnetic hot spots that are associated with cluster formation. We also compare the influence of plasmon excitation versus interband excitation on reaction thresholds, revealing that for silver clusters plasmon excitation leads to lower thresholds, but for gold clusters interband excitation is more effective. Our study also includes an analysis of charge transfer to and from the H₂ molecule, and a determination of orbital populations during and after the pulse, showing the correlation between metal excitations and the location of the antibonding level of H₂.

更新日期：2023-02-15

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