...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Wavelength and Temperature Dependence of the Femtosecond Pump-Probe Anisotropies in the Conjugated Polymer MEH-PPV:Implications for Energy-Transfer Dynamics
【24h】

Wavelength and Temperature Dependence of the Femtosecond Pump-Probe Anisotropies in the Conjugated Polymer MEH-PPV:Implications for Energy-Transfer Dynamics

机译：共轭聚合物MEH-PPV中飞秒泵浦-探针各向异性的波长和温度依赖性：对能量转移动力学的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Energy transfer in the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-l,4-phenylenevinylene](MEH-PPV)is investigated using femtosecond degenerate pump-probe experiments at 298 and 4 K.The polarization anisotropy decays are of the form exp[-(t)~(1/2)/T_pol],as predicted by theories of energy transfer in dilute chromophoric systems.At 4 K,these decays depend on the excitation wavelength,with T_pol=26 fs~(-1/2)at the peak of the absorption(520 nm)and T_pol=78 fs~~(-1/2)at the low-energy side of the absorption(580 nm).This wavelength dependence becomes less pronounced at higher temperatures but is always present.We find that models for Forster energy transfer in dilute chromophore solutions cannot describe our data using a single energy-transfer rate calculated from the Forster overlap of the steady-state absorption and emission spectra.The Forster radius R_0 obtained from fitting the experimental anisotropy decays does not agree with that obtained from the steady-state absorption and fluorescence spectra.This fact,along with the wavelength dependence of the anisotropy decays,indicates that the steady-state spectral properties alone are insufficient to explain the energy-transfer properties of MEH-PPV.By use of a simple model to account for inhomogeneous broadening,vibrational line shape,and the intramolecular Stokes shift,we obtain semiquantitative agreement with the experimental results.The key quantity in this modeling is the ratio of inhomogeneous to homogeneous broadening.As the temperature increases,this ratio decreases,leading to less wavelength dependence in the anisotropy decays.The agreement between our modeling and the data suggests that models developed to describe incoherent energy transfer in dilute solutions may be useful for predicting the energy-transport properties of amorphous conjugated polymers,as long as they are modified to take factors such as vibrational structure and inhomogeneous broadening into account.
机译：使用飞秒简并泵浦实验在298和4 K下研究了共轭聚合物聚[2-甲氧基-5-（2'-乙基己氧基）-1,4-亚苯基亚乙烯基]（MEH-PPV）中的能量转移。极化各向异性衰减的形式为exp [-（t）〜（1/2）/ T_pol]，如稀发色团中的能量转移理论所预测。在4 K时，这些衰减取决于激发波长，T_pol = 26 fs在吸收峰（520 nm）处约为〜（-1/2），在吸收低能侧（580 nm）处T_pol = 78 fs ~~（-1/2）。这种波长依赖性变得不太明显我们发现，在稀生色团溶液中Forster能量转移的模型无法使用从稳态吸收和发射光谱的Forster重叠计算出的单个能量转移速率来描述我们的数据.Forster半径R_0通过拟合实验各向异性衰减获得的结果与从稳态吸收获得的结果不一致这个事实以及各向异性衰减的波长依赖性表明，仅稳态光谱性质不足以解释MEH-PPV的能量转移性质。通过使用简单模型来解释不均匀增宽，振动线形和分子内斯托克斯位移，与实验结果获得了半定量的吻合。该模型的关键是不均匀与均匀增宽的比率。随着温度的升高，该比率降低，导致对波长的依赖性降低我们的模型与数据之间的一致性表明，描述为描述稀溶液中非相干能量转移而开发的模型可能对预测无定形共轭聚合物的能量传输性质有用，只要将它们修改为考虑以下因素即可：作为振动结构和不均匀扩展考虑。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号