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首页> 外文期刊>The Journal of Chemical Physics >Near-infrared optical-absorption behavior in high-beta nonlinear optical chromophore-polymer guest-host materials. II. Dye spacer length effects in an amorphous polycarbonate copolymer host - art. no. 234907
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Near-infrared optical-absorption behavior in high-beta nonlinear optical chromophore-polymer guest-host materials. II. Dye spacer length effects in an amorphous polycarbonate copolymer host - art. no. 234907

机译：高β非线性光学发色团-聚合物客体材料中的近红外光吸收行为。二。无定形聚碳酸酯共聚物主体中的染料间隔物长度效应-技术没有。 234907

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摘要

In the second of a three-part series, spectral absorption behavior of nonlinear optical (NLO) dyes incorporated into amorphous polycarbonate, comprised of a homologous series of dialkyl spacer groups extending from the midsection of the dye molecule, is characterized by UV-Vis and photothermal deflection spectroscopy. The dyes are structural analogs of the NLO dye FTC [2-(3-cyano-4-{2-[5-(2-{4-[ethyl-(2-methoxyethyl)amino]phenyl}vinyl)-3,4-diethylthiophen-2-yl]vinyl}-5,5-dimethyl-5H-furan-2-ylidene)malononitrile]. Previous Monte Carlo calculations [B. H. Robinson and L. R. Dalton, J. Phys. Chem. A 104, 4785 (2000)] predict a strong dependence of the macroscopic nonlinear optical susceptibility on the chromophore waist: length aspect ratio in electric-field-poled films arising from interactions between chromophores. It is expected that these interactions will play a role in the absorption characteristics of unpoled films, as well. The spacer groups range in length from diethyl to dihexyl, and each dye is studied over a wide range of concentrations. Among the four dyes studied, a universal dependence of near-IR loss on inhomogeneous broadening of the dye main absorption peak is found. The inhomogeneous width and its concentration dependence are seen to vary with spacer length in a manner characteristic of the near-IR loss-concentration slope at transmission wavelengths of 1.06 and 1.3 mu m, but not at 1.55 mu m. The lower wavelength loss behavior is assigned to purely Gaussian broadening, and is described by classical mixing thermodynamic quantities based on the Marcus theory of inhomogeneous broadening [R. A. Marcus, J. Chem. Phys. 43, 1261 (1965)], modeled as a convolution of dye-dye dipole broadening and dye-polymer van der Waals broadening. The Gaussian dipole interactions follow a Loring dipole-broadening description [R. F. Loring, J. Phys. Chem. 94, 513 (1990)] dominated by the excited-state dipole moment, and have a correlated homogeneous broadening contribution. The long-wavelength loss behavior has a non-Gaussian dye-dye dipole contribution which follows Kador's broadening analysis [L. Kador, J. Chem. Phys. 95, 5574 (1991)], with a net broadening described by a convolution of this term with a Gaussian van der Waals interaction given by Obata [M. Obata, S. Machida, and K. Horie, J. Polym. Sci. B 37, 2173 (1999)], with each term governed by the dye spacer length. A minimum in broadening and loss-concentration slope at a spacer length of four carbons per alkyl at all wavelengths has important consequences for practical waveguide devices, and is of higher aspect ratio than the spherical limit shown by Robinson and Dalton to minimize dipole interactions under a poling field. (C) 2005 American Institute of Physics.
机译：在三部分系列的第二部分中，掺入无定形聚碳酸酯中的非线性光学（NLO）染料的光谱吸收行为由UV-Vis和光热偏转光谱。该染料是NLO染料FTC [2-（3-氰基-4- {2- [5-（2- {4- [乙基-（2-甲氧基乙基）氨基]苯基]乙烯基} -3,4）结构类似物-二乙基噻吩-2-基]乙烯基} -5，5-二甲基-5H-呋喃-2-亚烷基）丙二腈]。以前的蒙特卡洛计算[B. H. Robinson和L. R. Dalton，J. Phys。化学A 104，4785（2000）]预测宏观非线性光学敏感性对发色团腰部的强烈依赖性：由于发色团之间的相互作用，电场极化膜中的长度长宽比大。预期这些相互作用也将在未极化膜的吸收特性中起作用。间隔基团的长度范围从二乙基到二己基，并且每种染料都在很宽的浓度范围内进行了研究。在研究的四种染料中，发现近红外损耗普遍依赖于染料主吸收峰的不均匀加宽。可见不均匀宽度及其浓度依赖性随间隔物长度而变化，其方式是在1.06和1.3μm的透射波长下具有近红外损耗浓度斜率，而在1.55μm处则没有。较低的波长损耗行为被分配给纯粹的高斯展宽，并由基于不均匀展宽的Marcus理论的经典混合热力学量来描述[R。 A.Marcus，J.Chem。物理43，1261（1965）]，以染料-染料偶极展宽和染料-聚合物范德华展宽的卷积为模型。高斯偶极子相互作用遵循Loring偶极子扩张的描述[R. F.Loring，J.Phys。化学94，513（1990）]由激发态偶极矩控制，并具有相关的均匀展宽作用。长波损耗行为具有非高斯染料染料偶极子贡献，这遵循了Kador的扩展分析[L. Kador，J.Chem。物理95，5574（1991）]，用该术语与Obata所给出的高斯范德华相互作用的卷积来描述净扩展。 Obata，S。Machida和K. Horie，J。Polym。科学B 37，2173（1999）]，每个术语均由染料间隔基长度决定。在所有波长下，每烷基含四个碳原子的间隔物长度处的加宽和损失浓度斜率的最小值，对实际的波导器件具有重要意义，并且其纵横比比Robinson和Dalton所示的球形极限值高，以最大程度地降低偶极子相互作用。极化场。 （C）2005美国物理研究所。

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