Coherent Multi-Quantum Multi-Dimensional Spectroscopy

相干多量子多维光谱

• 批准号: 423942615
• 负责人: Professor Dr. Tobias Brixner
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423942615?language=en
• 关键词: Coherent; Multi; Quantum; Dimensional; Spectroscopy

Coherent two-dimensional (2D) electronic spectroscopy is a powerful method for investigating exciton dynamics, energy and charge transport, or chemical reactions on ultrafast time scales. Providing frequency resolution both for the excitation and the detection separates contributions that overlap in one-dimensional transient absorption. The 2D method reveals the full third-order response function of light-matter interaction.Here we extend the concept systematically to higher nonlinear orders, higher quantum coherences, and higher dimensions. This offers unique information on excitons not accessible via other techniques. Using the developed methods, we plan to study the structure, dynamics, and correlations of electronically excited states in molecular and supramolecular species as well as quantum dots. This will be accomplished by femtosecond pulse shaping with shot-to-shot modulation at the 1-kHz repetition rate of the laser. Thus we can extract various nonlinear signal contributions via “phase cycling” from the same raw data set without changing the beam geometry. Rapid scanning significantly improves the signal-to-noise ratio and reduces the total data acquisition time.Our first approach is based on all-collinear excitation and fluorescence detection that avoids nonresonant solvent contributions. We will implement 1*4*4-, 1*6*6-, and 1*8*8-fold phase cycling to determine fourth-, sixth-, and eighth-order signals, respectively. Thus one can extract electron correlation energies or exciton binding energies. Moving to four-pulse sequences at 1*5*5*5=125-fold phase cycling reveals dynamic information within 15 different fourth- and sixth-order three-dimensional spectra that correlate various zero-, one-, two-, and three-quantum coherences with each other.A second approach employs a pump-probe geometry with measurement of the coherently emitted signal. Here we will use fifth-order exciton-exciton-interaction 2D spectroscopy to reveal exciton transport under systematic variation of supramolecular parameters such as chain length, geometry, or composition. We will also investigate systems in which transport may occur either along one, two, or three dimensions.Finally, we plan to compare the two excitation geometries by employing them on the same system using identical laser parameters. This should resolve a debate on the interpretation of 2D fluorescence spectra. In addition, we investigate the potential of four- and five-dimensional spectroscopy by deploying up to six pulses. This can disentangle all signal contributions up to sixth order and separate, for example, wavepacket dynamics on different electronic states that overlap in conventional 2D measurements.

相干二维（2D）电子光谱是研究激子动力学、能量和电荷输运或超快时间尺度上的化学反应的有力方法。为激发和检测提供频率分辨率分离了在一维瞬态吸收中重叠的贡献。二维方法揭示了光-物质相互作用的完整的三阶响应函数，本文将这一概念系统地推广到更高的非线性阶数、更高的量子相干性和更高的维数。这提供了通过其他技术无法获得的关于激子的独特信息。使用开发的方法，我们计划研究分子和超分子物种以及量子点的电子激发态的结构，动力学和相关性。这将通过飞秒脉冲整形和1 kHz激光重复率下的逐点调制来实现。因此，我们可以提取各种非线性信号的贡献，通过“相位循环”从相同的原始数据集，而不改变光束的几何形状。快速扫描显着提高了信噪比，减少了总的数据采集时间。我们的第一种方法是基于全共线激发和荧光检测，避免非共振溶剂的贡献。我们将实现1*4*4、1*6*6和1*8*8倍相位循环，以分别确定四阶、六阶和八阶信号。因此，可以提取电子相关能或激子结合能。移动到1*5*5*5=125倍相位循环的四脉冲序列，揭示了15个不同的四阶和六阶三维光谱内的动态信息，这些光谱将各种零、一、二和三量子相干相互关联。第二种方法采用泵浦-探测几何结构，测量相干发射信号。在这里，我们将使用五阶激子激子相互作用的二维光谱，揭示激子输运下的超分子参数，如链长，几何形状，或组成的系统变化。我们也将研究系统中的传输可能发生沿着一，二，或three-dimensions.Finally，我们计划比较两个激发几何形状，通过使用相同的激光参数在同一系统上使用它们。这应该解决了关于二维荧光光谱解释的争论。此外，我们调查的潜力，四维和五维光谱部署多达六个脉冲。这可以解开所有信号的贡献高达六阶和分离，例如，在传统的2D测量重叠的不同电子状态的波包动力学。