Asymmetrical Spectral Continuum between Anti-Stokes and Stokes Scattering Revealed in Low-Frequency Surface-Enhanced Raman Spectroscopy

Authors

Shuo Sun, University of Nebraska-LincolnFollow
Dhanusha T.N. Rathnayake, University of Nebraska-LincolnFollow
Yinsheng Guo, University of Nebraska-LincolnFollow

ORCID IDs

Y. Guo https://orcid.org/0000-0002-0571-8447

Date of this Version

6-28-2022

Citation

Published in Journal of Physical Chemistry C 2022, 126, 11193−11200 doi:10.1021/acs.jpcc.2c02486

Comments

Copyright © 2022 American Chemical Society. Used by permission.

Abstract

An asymmetrical spectral continuum is observed in low-frequency surface-enhanced Raman spectroscopy (LF-SERS) in the terahertz (THz) region. This background continuum appears as a flat baseline in the Stokes side and a slope in the anti-Stokes side. Analysis shows this asymmetry originates from the different scaling of anti-Stokes and Stokes scattering with respect to the Bose−Einstein distribution. Such asymmetry is readily visible, under room temperature, in the low-frequency THz spectral range. Accounting for this spectral intensity asymmetry reveals the intrinsic continuum background of electronic origin, differing from local normal modes and collective relaxational motions. We also describe a numerical method, independent of line shape models, to determine sample temperatures while simultaneously accounting for this asymmetrical background continuum. Finally, we show that such asymmetrical spectral continuum is generally observable in low-frequency Raman scattering.