Beyond Equilibrium Raman Thermometry: Fermi-Level Control of the Anti-Stokes Response in Graphene
Abstract
Non-equilibrium electron and phonon populations govern heat generation and dissipation in nanoscale devices, yet their direct characterization remains challenging. Anti-Stokes Raman scattering provides a sensitive probe of phonon populations and local temperatures, although its interpretation becomes more complex when electronic and phononic populations are driven out of equilibrium. Here, we investigate the gate-dependent anti-Stokes Raman response of monolayer graphene and find that the anti-Stokes response deviates from that expected from an equilibrium phonon population. Using a spatially localized microdroplet spectroelectrochemical platform, dielectric back-gates, and chemical doping, we observe a strong and reversible suppression of the G-mode anti-Stokes intensity as the Fermi level is tuned away from the Dirac point, while the Stokes intensity remains essentially unchanged. By contrast, the G-mode frequency and linewidth of both the Stokes and anti-Stokes branches evolve with doping as expected from the established Kohn-anomaly picture. The anti-Stokes/Stokes intensity ratio decreases by several-fold over the measured range and displays a pronounced, gate-dependent power response with maximum sensitivity at charge neutrality. Comparison with previous studies of non-equilibrium carrier dynamics in doped graphene suggests an important role of Fermi-level-dependent electronic phase space, which can influence both hot-carrier-driven phonon populations and electronically mediated Stokes-anti-Stokes scattering. Our findings establish anti-Stokes Raman scattering as a sensitive probe of electron-phonon coupling and non-equilibrium phonon dynamics in graphene.
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BibTeX
@misc{jindra2026beyond,
title = {{Beyond Equilibrium Raman Thermometry: Fermi-Level Control of the Anti-Stokes Response in Graphene}},
author = {Martin Jindra and Luka Pirker and Tim Verhagen and Ciarán Fowley and Martin Kalbáč and Matěj Velický and Riichiro Saito and Ado Jorio and Otakar Frank},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10159},
eprint = {2610.10159},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10159},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Beyond Equilibrium Raman Thermometry: Fermi-Level Control of the Anti-Stokes Response in Graphene
AU - Martin Jindra
AU - Luka Pirker
AU - Tim Verhagen
AU - Ciarán Fowley
AU - Martin Kalbáč
AU - Matěj Velický
AU - Riichiro Saito
AU - Ado Jorio
AU - Otakar Frank
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.10159
UR - https://arxiv.org/abs/2610.10159
AB - Non-equilibrium electron and phonon populations govern heat generation and dissipation in nanoscale devices, yet their direct characterization remains challenging. Anti-Stokes Raman scattering provides a sensitive probe of phonon populations and local temperatures, although its interpretation becomes more complex when electronic and phononic populations are driven out of equilibrium. Here, we investigate the gate-dependent anti-Stokes Raman response of monolayer graphene and find that the anti-Stokes response deviates from that expected from an equilibrium phonon population. Using a spatially localized microdroplet spectroelectrochemical platform, dielectric back-gates, and chemical doping, we observe a strong and reversible suppression of the G-mode anti-Stokes intensity as the Fermi level is tuned away from the Dirac point, while the Stokes intensity remains essentially unchanged. By contrast, the G-mode frequency and linewidth of both the Stokes and anti-Stokes branches evolve with doping as expected from the established Kohn-anomaly picture. The anti-Stokes/Stokes intensity ratio decreases by several-fold over the measured range and displays a pronounced, gate-dependent power response with maximum sensitivity at charge neutrality. Comparison with previous studies of non-equilibrium carrier dynamics in doped graphene suggests an important role of Fermi-level-dependent electronic phase space, which can influence both hot-carrier-driven phonon populations and electronically mediated Stokes-anti-Stokes scattering. Our findings establish anti-Stokes Raman scattering as a sensitive probe of electron-phonon coupling and non-equilibrium phonon dynamics in graphene.
ER -