Coupling between Harmonic Vibrations Influences Quantum Beating Signatures in Two-Dimensional Electronic Spectra

Jonathan D. Schultz, Taeyeon Kim, James P. O’Connor, Ryan M. Young, Michael R. Wasielewski*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Launching and tracking wavepacket dynamics with two-dimensional electronic spectroscopy (2DES) provides insight into the complex interactions that underlie coherent processes within photoactive materials. With the ever-growing interest in how electronic-vibrational (vibronic) interactions direct ultrafast photophysics, methods for translating 2DES results into meaningful descriptions of the molecular potential energy landscape must evolve correspondingly. The interpretation of quantum beatmaps, which provide direct insight into the intra- and interchromophoric couplings within a chemical system, frequently relies on physical models that account for a single nuclear coordinate. However, several recent works suggest that coupling between wavepackets borne from several different vibrational motions affects 2DES data in meaningful ways. We build upon these insights by directly comparing simulations using single- and multicomponent vibronic Hamiltonians against experimental 2DES results from the organic semiconductors terrylenediimide and ITIC, as well as the biomedical dyes methylene blue and Nile blue A. We show that the experimental beatmaps and Fourier power spectra are well-reproduced when both low- and high-frequency vibrational motions are included in the simulation. Moreover, we demonstrate that the interaction of harmonic wavepackets increases quantum beat amplitudes in the positive-frequency rephasing signals, which significantly complicates standard methods for separating ground- and excited-state vibrational coherence signatures from 2DES data. These findings illustrate that coupling between purely harmonic vibrational wavepackets can have significant and prevalent effects on experimental 2DES results.

Original languageEnglish (US)
Pages (from-to)120-131
Number of pages12
JournalJournal of Physical Chemistry C
Volume126
Issue number1
DOIs
StatePublished - Jan 13 2022

Funding

We thank Professor Roel Tempelaar and Professor Jae Yoon Shin for insightful discussions pertaining to the simulations and experimental comparisons conducted for this work, Dr. Itai Schlesinger for fruitful conversations regarding the physical interpretation of harmonic coupling, Dr. Xingang Zhao and Dr. Michelle Chen for synthesizing TDI, and Gyeongwon Kang, Dr. Leighton Jones, and Professor Martin Mosquera for helpful discussions regarding resonance Raman DFT computations with the ADF software package. This work was supported by the National Science Foundation under Award CHE-1925690 (M.R.W.). This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1842165 (J.D.S.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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