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Donatas Zigmantas. Portrait.

Donatas Zigmantas

Professor

Donatas Zigmantas. Portrait.

Dynamic band-shift signal in two-dimensional electronic spectroscopy : A case of bacterial reaction center

Author

  • Eglė Bukartė
  • David Paleček
  • Petra Edlund
  • Sebastian Westenhoff
  • Donatas Zigmantas

Summary, in English

Optical nonlinear spectroscopies carry a high amount of information about the systems under investigation; however, as they report polarization signals, the resulting spectra are often congested and difficult to interpret. To recover the landscape of energy states and physical processes such as energy and electron transfer, a clear interpretation of the nonlinear signals is prerequisite. Here, we focus on the interpretation of the electrochromic band-shift signal, which is generated when an internal electric field is established in the system following optical excitation. Whereas the derivative shape of the band-shift signal is well understood in transient absorption spectroscopy, its emergence in two-dimensional electronic spectroscopy (2DES) has not been discussed. In this work, we employed 2DES to follow the dynamic band-shift signal in reaction centers of purple bacteria Rhodobacter sphaeroides at 77 K. The prominent two-dimensional derivative-shape signal appears with the characteristic formation time of the charge separated state. To explain and characterize the band-shift signal, we use expanded double-sided Feynman diagram formalism. We propose to distinguish two types of Feynman diagrams that lead to signals with negative amplitude: excited state absorption and re-excitation. The presented signal decomposition and modeling analysis allows us to recover precise electrochromic shifts of accessory bacteriochlorophylls, identify additional signals in the B band range, and gain a further insight into the electron transfer mechanism. In a broader perspective, expanded Feynman diagram formalism will allow for interpretation of all 2D signals in a clearer and more intuitive way and therefore facilitate studying the underlying photophysics.

Department/s

  • Chemical Physics
  • NanoLund: Centre for Nanoscience

Publishing year

2021

Language

English

Publication/Series

Journal of Chemical Physics

Volume

154

Issue

11

Document type

Journal article

Publisher

American Institute of Physics (AIP)

Topic

  • Physical Chemistry (including Surface- and Colloid Chemistry)
  • Atom and Molecular Physics and Optics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0021-9606