Barclay Matthew S, Cunningham Paul D, Pascual Gissela, Roy Simon K, Patten Lance K, Susumu Kimihiro, Policht Veronica R, Mathur Divita, Meares Adam, Lee Jeunghoon, Yurke Bernard, Knowlton William B, Davis Paul H, Pensack Ryan D, Medintz Igor L, Melinger Joseph S, Turner Daniel B
Micron School of Materials Science and Engineering, Boise State University, Boise, Idaho 83725, USA.
Electronics Science and Technology Division Code 6800, U.S. Naval Research Laboratory, Washington, District of Columbia 20375, USA.
J Chem Phys. 2025 May 7;162(17). doi: 10.1063/5.0258934.
Packing conformations of molecular aggregates are known to strongly influence the locations and intensities of spectral peaks. Here, we develop the third-order nonlinear spectroscopy signals for a purely electronic model of a molecular dimer, which is a prototype aggregate system. The model-which focuses on excited-state absorption (ESA) pathways in two-dimensional electronic spectra-reveals that orientational averaging leads to diagnostic ESA peak locations for H- and J-dimers. We constructed DNA-templated dimers of cyanine molecules as representative systems and used ultrabroadband two-dimensional electronic spectroscopy measurements to support the predicted signatures arising from the theoretical model. Fitting of steady-state spectra supports the assigned packing conformations. The results elucidate how ESA peaks can be diagnostic spectral signatures of packing conformation. This work lays the foundation for future studies that can include the complicating effects of vibronic states and additional electronic levels.
分子聚集体的堆积构象已知会强烈影响光谱峰的位置和强度。在这里，我们为分子二聚体的纯电子模型开发了三阶非线性光谱信号，分子二聚体是一种典型的聚集体系统。该模型专注于二维电子光谱中的激发态吸收（ESA）途径，揭示了取向平均导致H型和J型二聚体的诊断性ESA峰位置。我们构建了花菁分子的DNA模板二聚体作为代表性系统，并使用超宽带二维电子光谱测量来支持理论模型产生的预测特征。稳态光谱的拟合支持所指定的堆积构象。结果阐明了ESA峰如何能够成为堆积构象的诊断光谱特征。这项工作为未来的研究奠定了基础，这些研究可以包括振动态和额外电子能级的复杂影响。
