Jump to main content
Jump to site search

Issue 28, 2017
Previous Article Next Article

Substrate influence on the interlayer electron–phonon couplings in fullerene films probed with doubly-resonant SFG spectroscopy

Author affiliations

Abstract

We present doubly-resonant sum frequency generation (DR-SFG) spectra of fullerene thin films on metallic and dielectric substrates as a way to investigate the interplay between nuclear and electronic coupling at buried interfaces. Modal and substrate selectivity in the electronic enhancement of the C60 vibrational signatures is demonstrated for excitation wavelengths spanning the visible range. While the SFG response of the totally symmetric Ag(2) mode of fullerene is distinctly coupled to the optically allowed electronic transition corresponding to the HOMO–LUMO+1 of C60 (ca. 2.6 eV), the T1u(4) vibrational mode appears to be coupled to a symmetry-forbidden HOMO–LUMO transition at lower energies (ca. 2.0 eV). For dielectric substrates, the DR-SFG intensity of the T1u(4) mode shows lack of enhancement for upconversion wavelengths off-resonance with the optically-dark LUMO. However, the T1u(4) mode shows a unique coupling to an intermediate state (∼2.4 eV) only for the fullerene films on the gold substrate. We attribute this coupling to unique interactions at the buried C60/gold interface. These results demonstrate the occurrence of clear electron–phonon couplings at the C60/substrate interfaces and shed light on the impact of these couplings on the optical response of electronically excited fullerene. This coupling may influence charge and energy transport in organic electronic devices mediated by vibrational motions. We also demonstrate a potential use of this added selectivity in chemical imaging.

Graphical abstract: Substrate influence on the interlayer electron–phonon couplings in fullerene films probed with doubly-resonant SFG spectroscopy

Back to tab navigation

Supplementary files

Publication details

The article was received on 15 May 2017, accepted on 30 Jun 2017 and first published on 30 Jun 2017


Article type: Paper
DOI: 10.1039/C7CP03115G
Citation: Phys. Chem. Chem. Phys., 2017,19, 18519-18528
  •   Request permissions

    Substrate influence on the interlayer electron–phonon couplings in fullerene films probed with doubly-resonant SFG spectroscopy

    D. Elsenbeck, S. K. Das and L. Velarde, Phys. Chem. Chem. Phys., 2017, 19, 18519
    DOI: 10.1039/C7CP03115G

Search articles by author

Spotlight

Advertisements