skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Vibronic phenomena and exciton–vibrational interference in two-dimensional spectra of molecular aggregates

Abstract

A general theory of electronic excitations in aggregates of molecules coupled to intramolecular vibrations and the harmonic environment is developed for simulation of the third-order nonlinear spectroscopy signals. It is applied in studies of the time-resolved two-dimensional coherent spectra of four characteristic model systems: weakly/strongly vibronically coupled molecular dimers interacting with high/low frequency intramolecular vibrations. The results allow us to (i) classify and define the typical spectroscopic features of vibronically coupled molecules, (ii) separate the cases, when the long-lived quantum coherences due to vibrational lifetime borrowing should be expected, (iii) define when the complete exciton–vibrational mixing occurs, and (iv) when separation of excitonic and vibrational coherences is possible.

Authors:
;  [1];  [2];  [1]
  1. Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius (Lithuania)
  2. (Lithuania)
Publication Date:
OSTI Identifier:
22255264
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DIMERS; EXCITATION; INTERFERENCE; MOLECULES; SIGNALS; SIMULATION; SPECTRA; SPECTROSCOPY; TIME RESOLUTION

Citation Formats

Butkus, Vytautas, Valkunas, Leonas, Center for Physical Sciences and Technology, Gostauto 9, 01108 Vilnius, and Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt. Vibronic phenomena and exciton–vibrational interference in two-dimensional spectra of molecular aggregates. United States: N. p., 2014. Web. doi:10.1063/1.4861466.
Butkus, Vytautas, Valkunas, Leonas, Center for Physical Sciences and Technology, Gostauto 9, 01108 Vilnius, & Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt. Vibronic phenomena and exciton–vibrational interference in two-dimensional spectra of molecular aggregates. United States. doi:10.1063/1.4861466.
Butkus, Vytautas, Valkunas, Leonas, Center for Physical Sciences and Technology, Gostauto 9, 01108 Vilnius, and Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt. Tue . "Vibronic phenomena and exciton–vibrational interference in two-dimensional spectra of molecular aggregates". United States. doi:10.1063/1.4861466.
@article{osti_22255264,
title = {Vibronic phenomena and exciton–vibrational interference in two-dimensional spectra of molecular aggregates},
author = {Butkus, Vytautas and Valkunas, Leonas and Center for Physical Sciences and Technology, Gostauto 9, 01108 Vilnius and Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt},
abstractNote = {A general theory of electronic excitations in aggregates of molecules coupled to intramolecular vibrations and the harmonic environment is developed for simulation of the third-order nonlinear spectroscopy signals. It is applied in studies of the time-resolved two-dimensional coherent spectra of four characteristic model systems: weakly/strongly vibronically coupled molecular dimers interacting with high/low frequency intramolecular vibrations. The results allow us to (i) classify and define the typical spectroscopic features of vibronically coupled molecules, (ii) separate the cases, when the long-lived quantum coherences due to vibrational lifetime borrowing should be expected, (iii) define when the complete exciton–vibrational mixing occurs, and (iv) when separation of excitonic and vibrational coherences is possible.},
doi = {10.1063/1.4861466},
journal = {Journal of Chemical Physics},
number = 3,
volume = 140,
place = {United States},
year = {Tue Jan 21 00:00:00 EST 2014},
month = {Tue Jan 21 00:00:00 EST 2014}
}
  • Cited by 2
  • The properties of polaritons in J-aggregate microcavities are explored using a Hamiltonian which treats exciton-vibrational coupling and exciton-photon coupling on equal footing. When the cavity mode is resonant with the lowest-energy (0-0) transition in the J-aggregate, two polaritons are formed, the lowest-energy polariton (LP) and its higher-energy partner (P{sub 1}), separated by the Rabi splitting. Strong coupling between the material and cavity modes leads to a decoupling of the exciton and vibrational degrees of freedom and an overall reduction of disorder within the LP. Such effects lead to an expanded material coherence length in the LP which leads to enhancedmore » radiative decay rates. Additional spectral signatures include an amplification of the 0-0 peak coincident with a reduction in the 0-1 peak in the photoluminescence spectrum. It is also shown that the same cavity photon responsible for the LP/P{sub 1} splitting causes comparable splittings in the higher vibronic bands due to additional resonances between vibrationally excited states in the electronic ground state manifold and higher energy vibronic excitons.« less
  • We theoretically investigate the photon-echo spectroscopy of coupled electron-nuclear quantum dynamics. Two situations are treated. In the first case, the Born-Oppenheimer (adiabatic) approximation holds. It is then possible to interpret the two-dimensional (2D) spectra in terms of vibrational motion taking place in different electronic states. In particular, pure vibrational coherences which are related to oscillations in the time-dependent third-order polarization can be identified. This concept fails in the second case, where strong non-adiabatic coupling leads to the breakdown of the Born-Oppenheimer-approximation. Then, the 2D-spectra reveal a complicated vibronic structure and vibrational coherences cannot be disentangled from the electronic motion.
  • Coherent multidimensional optical spectroscopy is an emerging technique for resolving structure and ultrafast dynamics of molecules, proteins, semiconductors, and other materials. A current challenge is the quality of kinetics that are examined as a function of waiting time. Inspired by noise-suppression methods of transient absorption, here we incorporate shot-by-shot acquisitions and balanced detection into coherent multidimensional optical spectroscopy. We demonstrate that implementing noise-suppression methods in two-dimensional electronic spectroscopy not only improves the quality of features in individual spectra but also increases the sensitivity to ultrafast time-dependent changes in the spectral features. Measurements on cresyl violet perchlorate are consistent with themore » vibronic pattern predicted by theoretical models of a highly displaced harmonic oscillator. The noise-suppression methods should benefit research into coherent electronic dynamics, and they can be adapted to multidimensional spectroscopies across the infrared and ultraviolet frequency ranges.« less
  • No abstract prepared.