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Linear and Nonlinear Optical Properties of Functional Groups for Conjugated Polymers. Analysis of the Acceptor-Donor Pair Substituents of Benzene: The Case of meta-Nitroaniline.
ACS Omega ( IF 4.1 ) Pub Date : 2019-12-27 , DOI: 10.1021/acsomega.9b03063 Cesar A Guarin 1 , Javier Alejandro Díaz Ponce 1
ACS Omega ( IF 4.1 ) Pub Date : 2019-12-27 , DOI: 10.1021/acsomega.9b03063 Cesar A Guarin 1 , Javier Alejandro Díaz Ponce 1
Affiliation
The nonlinear optical (NLO) properties of meta-nitroaniline (m-NA) are evaluated via Hückel-Agrawal's approximation in a solvent environment. In this context, both the 1B and the intramolecular charge transfer (ICT) electronic transitions are considered. The benzene ring currents on the clockwise or counterclockwise direction and the corresponding Brillouin zone from 0 to π are also considered. Besides, the Bloch equations were applied to a single cell n = 1 defined on the benzene ring. We have considered that the light beam was directed along the ring benzene bonds of m-NA; this topological hypothesis changed the crystal structure to a linear chain and the calculated optical properties were found near the experimental ones. In addition, the Fermi's golden rule was applied to the crystal state and then the calculated refraction index of m-NA had an error of less than 3% of the experimental one. On the other hand, the molar absorptivity ε of m-NA in acetonitrile for the 1B and intramolecular ICT transitions was experimentally determined to be 11 981 and 1192 L mol-1 cm-1, respectively. With this methodology, we found that the change of the charge in the NO2 group has also a strong influence on the linear and NLO properties. In addition, the dipole transition moments, which are originated from the carbon between the carbons joined to NO2 and NH2, are mainly involved in the NLO properties. Thus, the first hyperpolarizability β z was 1.69 × 10-30 esu at λLaser = 1064 nm, 27% of the experimental value. We attribute this difference to the evaluation of the excited dipole moment. If we attribute a separation of charge of 0.1 e in the excited state, the new dipole moment allows for the simulation of the experimental value. Besides, the calculated value of χ(3) for m-NA in a solution of acetonitrile is 2.9 × 10-13 esu at λLaser = 1064 nm, 158% of the experimental value. The discrepancy between these values is attributed to the influence of the electronic correlation effects, that is, because of resonance structures of the aromatic ring and the zwitterionic pair of nitro and aniline. Besides, we have also evaluated the second hyperpolarizability γ, the second-order susceptibility χ(2) of m-NA and their values have similar differences to the experimental values. This type of approach is important because it reduces computing time and gives insight into the molecular causes responsible for linear and NLO properties in this type of functional groups, which can be used as building blocks in more complex polymer systems.
中文翻译:
共轭聚合物官能团的线性和非线性光学性质。苯的受体-供体对取代基的分析:以间硝基苯胺为例。
通过Hückel-Agrawal近似在溶剂环境中评估间硝基苯胺(m-NA)的非线性光学(NLO)特性。在这种情况下,同时考虑了1B和分子内电荷转移(ICT)电子跃迁。还考虑了顺时针或逆时针方向的苯环电流以及相应的从0到π的布里渊区。此外,将Bloch方程应用于在苯环上定义的单个单元n = 1。我们认为光束是沿着m-NA的环苯键导向的;这种拓扑假说将晶体结构改变为线性链,并在实验附近找到了计算的光学性质。此外,费米 将s黄金法则应用于晶体状态,然后计算出的m-NA折射率的误差小于实验值的3%。另一方面,通过实验确定,乙腈中m-NA在1B和分子内ICT跃迁中的摩尔吸收率ε分别为11 981和1192 L mol-1 cm-1。通过这种方法,我们发现NO2基团中电荷的变化对线性和NLO性质也有很大的影响。此外,偶合跃迁矩主要涉及NLO性质,该偶极跃迁矩起源于与NO2和NH2连接的碳之间的碳。因此,第一超极化率βz在λLaser= 1064 nm时为1.69×10-30 esu,是实验值的27%。我们将此差异归因于对激发偶极矩的评估。如果我们将激发态下的电荷分离定为0.1 e,则新的偶极矩可以模拟实验值。此外,在λLaser= 1064 nm时,乙腈溶液中m-NA的χ(3)的计算值为2.9×10-13 esu,为实验值的158%。这些值之间的差异归因于电子相关效应的影响,即由于芳香环以及硝基和苯胺的两性离子对的共振结构。此外,我们还评估了m-NA的二次超极化率γ,二次磁化率χ(2),其值与实验值具有相似的差异。
更新日期:2020-01-14
中文翻译:
共轭聚合物官能团的线性和非线性光学性质。苯的受体-供体对取代基的分析:以间硝基苯胺为例。
通过Hückel-Agrawal近似在溶剂环境中评估间硝基苯胺(m-NA)的非线性光学(NLO)特性。在这种情况下,同时考虑了1B和分子内电荷转移(ICT)电子跃迁。还考虑了顺时针或逆时针方向的苯环电流以及相应的从0到π的布里渊区。此外,将Bloch方程应用于在苯环上定义的单个单元n = 1。我们认为光束是沿着m-NA的环苯键导向的;这种拓扑假说将晶体结构改变为线性链,并在实验附近找到了计算的光学性质。此外,费米 将s黄金法则应用于晶体状态,然后计算出的m-NA折射率的误差小于实验值的3%。另一方面,通过实验确定,乙腈中m-NA在1B和分子内ICT跃迁中的摩尔吸收率ε分别为11 981和1192 L mol-1 cm-1。通过这种方法,我们发现NO2基团中电荷的变化对线性和NLO性质也有很大的影响。此外,偶合跃迁矩主要涉及NLO性质,该偶极跃迁矩起源于与NO2和NH2连接的碳之间的碳。因此,第一超极化率βz在λLaser= 1064 nm时为1.69×10-30 esu,是实验值的27%。我们将此差异归因于对激发偶极矩的评估。如果我们将激发态下的电荷分离定为0.1 e,则新的偶极矩可以模拟实验值。此外,在λLaser= 1064 nm时,乙腈溶液中m-NA的χ(3)的计算值为2.9×10-13 esu,为实验值的158%。这些值之间的差异归因于电子相关效应的影响,即由于芳香环以及硝基和苯胺的两性离子对的共振结构。此外,我们还评估了m-NA的二次超极化率γ,二次磁化率χ(2),其值与实验值具有相似的差异。