title: Controlling quantum-beating signals in 2D electronic spectra by packing synthetic heterodimers on single-walled carbon nanotubes.
abstract: In multidimensional spectroscopy, dynamics of coherences between excited states report on the interactions between electronic states and their environment. The prolonged coherence lifetimes revealed through beating signals in the spectra of some systems may result from vibronic coupling between nearly degenerate excited states, and recent observations confirm the existence of such coupling in both model systems and photosynthetic complexes. Understanding the origin of beating signals in the spectra of photosynthetic complexes has been given considerable attention; however, strategies to generate them in artificial systems that would allow us to test the hypotheses in detail are still lacking. Here we demonstrate control over the presence of quantum-beating signals by packing structurally flexible synthetic heterodimers on single-walled carbon nanotubes, and thereby restrict the motions of chromophores. Using two-dimensional electronic spectroscopy, we find that both limiting the relative rotation of chromophores and tuning the energy difference between the two electronic transitions in the dimer to match a vibrational mode of the lower-energy monomer are necessary to enhance the observed quantum-beating signals.
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Graham B
authors.initials: GB
authors.lastname: Griffin
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Alice
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhai
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Williams
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Richard F
authors.initials: RF
authors.lastname: Jordan
authors.affiliation: Department of Chemistry, James Franck Institute, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: Gregory S
authors.identifier: 0000-0002-6740-5243
authors.initials: GS
authors.lastname: Engel
mesh_terms: D019281:Dimerization; D004583:Electrons; D019793:Fluorescein / Q000737:chemistry; D008968:Molecular Conformation; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman
chemical_list: D037742:Nanotubes, Carbon; D019793:Fluorescein