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Updated: May 7, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
The origin of relative intensity fluctuations in single-molecule tip-enhanced Raman spectroscopy
Matthew D Sonntag1, Dhabih Chulhai, Tamar Seideman
1Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
Abstract:
An explanation of the relative intensity fluctuations observed in single-molecule Raman experiments is described utilizing both single-molecule tip-enhanced Raman spectroscopy and time-dependent density functional theory calculations. No correlation is observed in mode to mode intensity fluctuations indicating that the changes in mode intensities are completely independent. Theoretical calculations provide convincing evidence that the fluctuations are not the result of diffusion, orientation, or local electromagnetic field gradients but rather are the result of subtle variations of the excited-state lifetime, energy, and geometry of the molecule. These variations in the excited-state properties will provide information on adsorbate-adsorbate and adsorbate-substrate interactions and may allow for inversion of experimental results to obtain these excited-state properties.
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