TY - JOUR
T1 - Coupling, lifetimes, and "strong coupling" maps for single molecules at plasmonic interfaces
AU - Mondal, Monosij
AU - Ochoa, Maicol A.
AU - Sukharev, Maxim
AU - Nitzan, Abraham
N1 - Funding Information:
M.S. acknowledges the financial support from the Air Force Office of Scientific Research under Grant No. FA9550-19-1-0009. A.N. acknowledges the support of the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division.
Publisher Copyright:
© 2022 Author(s).
PY - 2022/4/21
Y1 - 2022/4/21
N2 - The interaction between excited states of a molecule and excited states of a metal nanostructure (e.g., plasmons) leads to hybrid states with modified optical properties. When plasmon resonance is swept through molecular transition frequency, an avoided crossing may be observed, which is often regarded as a signature of strong coupling between plasmons and molecules. Such strong coupling is expected to be realized when 2|«U»|/hΓ > 1, where «U»and Γ are the molecule-plasmon coupling and the spectral width of the optical transition, respectively. Because both «U»and Γ strongly increase with decreasing distance between a molecule and a plasmonic structure, it is not obvious that this condition can be satisfied for any molecule-metal surface distance. In this work, we investigate the behavior of «U»and Γ for several geometries. Surprisingly, we find that if the only contributions to Γ are lifetime broadenings associated with the radiative and nonradiative relaxation of a single molecular vibronic transition, including effects on molecular radiative and nonradiative lifetimes induced by the metal, the criterion 2|«U»|/hΓ > 1 is easily satisfied by many configurations irrespective of the metal-molecule distance. This implies that the Rabi splitting can be observed in such structures if other sources of broadening are suppressed. Additionally, when the molecule-metal surface distance is varied keeping all other molecular and metal parameters constant, this behavior is mitigated due to the spectral shift associated with the same molecule-plasmon interaction, making the observation of Rabi splitting more challenging.
AB - The interaction between excited states of a molecule and excited states of a metal nanostructure (e.g., plasmons) leads to hybrid states with modified optical properties. When plasmon resonance is swept through molecular transition frequency, an avoided crossing may be observed, which is often regarded as a signature of strong coupling between plasmons and molecules. Such strong coupling is expected to be realized when 2|«U»|/hΓ > 1, where «U»and Γ are the molecule-plasmon coupling and the spectral width of the optical transition, respectively. Because both «U»and Γ strongly increase with decreasing distance between a molecule and a plasmonic structure, it is not obvious that this condition can be satisfied for any molecule-metal surface distance. In this work, we investigate the behavior of «U»and Γ for several geometries. Surprisingly, we find that if the only contributions to Γ are lifetime broadenings associated with the radiative and nonradiative relaxation of a single molecular vibronic transition, including effects on molecular radiative and nonradiative lifetimes induced by the metal, the criterion 2|«U»|/hΓ > 1 is easily satisfied by many configurations irrespective of the metal-molecule distance. This implies that the Rabi splitting can be observed in such structures if other sources of broadening are suppressed. Additionally, when the molecule-metal surface distance is varied keeping all other molecular and metal parameters constant, this behavior is mitigated due to the spectral shift associated with the same molecule-plasmon interaction, making the observation of Rabi splitting more challenging.
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U2 - 10.1063/5.0077739
DO - 10.1063/5.0077739
M3 - Article
C2 - 35459293
AN - SCOPUS:85128802361
SN - 0021-9606
VL - 156
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 15
M1 - 154303
ER -