Efficient Modeling of Organic Chromophores for Entangled Two-Photon Absorption
Efficient Modeling of Organic Chromophores for Entangled Two-Photon Absorption
复制标题
用于纠缠双光子吸收的有机发色团的有效建模
DOI：
10.1021/jacs.0c02808
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发表时间：
2020
影响因子：
15
通讯作者：
Schatz, George C.
中科院分区：
文献类型：
--
作者：
Kang, Gyeongwon;Nasiri Avanaki, Kobra;Mosquera, Martín A.;Burdick, Ryan K.;Villabona-Monsalve, Juan P.;Goodson, Theodore;Schatz, George C.
利用非经典光源研究分子的电子结构在许多应用中引起了极大的兴趣。在这里，我们报告的纠缠双光子吸收（ETPA）在有机发色团的理论研究，我们提供了新的见解ETPA和相应的非纠缠TPA之间的定量关系的基础上显着不同的线宽与纠缠和非纠缠过程。一个sum-over-states方法被用来获得经典的TPA和ETPA截面，并探讨每个电子状态的ETPA过程的贡献。从第二线性响应（SLR）TDDFT方法获得该计算所需的跃迁矩和能量[J. Chem. Phys.，2016，144，204105]，其能够处理用作双光子吸收剂的相对大的聚噻吩树枝状聚合物。此外，SLR计算提供了估计的激发态辐射线的宽度，我们涉及到纠缠的双光子态密度使用量子电动力学分析。该分析表明，对于所研究的树枝状聚合物，ETPA的线宽比TPA窄几个数量级，对应于具有大施密特数的高度纠缠光子。计算的截面与实验报道的值吻合得很好。我们还进行了状态解析分析，以揭示ETPA过程的途径，这些都表明显着的干扰行为。我们强调，在TPA过程中使用纠缠光子在探测量子极限下的光-物质干涉性质来探测分子的详细电子结构方面起着至关重要的作用。
The use of a nonclassical light source for studying molecular electronic structure has been of great interest in many applications. Here we report a theoretical study of entangled two-photon absorption (ETPA) in organic chromophores, and we provide new insight into the quantitative relation between ETPA and the corresponding unentangled TPA based on the significantly different line widths associated with entangled and unentangled processes. A sum-over-states approach is used to obtain classical TPA and ETPA cross sections and to explore the contribution of each electronic state to the ETPA process. The transition moments and energies needed for this calculation were obtained from a second linear-response (SLR) TDDFT method [J. Chem. Phys.,2016,144, 204105], which enables the treatment of relatively large polythiophene dendrimers that serve as two-photon absorbers. In addition, the SLR calculations provide estimates of the excited state radiative line width, which we relate to the entangled two-photon density of states using a quantum electrodynamic analysis. This analysis shows that for the dendrimers being studied, the line width for ETPA is orders of magnitude narrower than for TPA, corresponding to highly entangled photons with a large Schmidt number. The calculated cross sections are in good agreement with the experimentally reported values. We also carried out a state-resolved analysis to unveil pathways for the ETPA process, and these demonstrate significant interference behavior. We emphasize that the use of entangled photons in TPA process plays a critical role in probing the detailed electronic structure of a molecule by probing light-matter interference nature in the quantum limit.