Optimizing Resonant Raman Scattering in Monolayer

Resonance Raman scattering (RRS) is widely recognized for dramatically enhancing the intensity of Raman modes through the precise tuning of excitation energy to be resonant with the electronic transition energy in semiconductors. However, this work reports that in monolayer MoS2 flake (1LM), when the excitation energy is resonant with the A-exciton energy, the A′ 1 and E′ modes exhibit anomalous quenching of the Raman intensity, which is even comparable to that under the non-resonant condition. This unusually weakened resonant Raman intensity is ascribed to the band filling effect (BFE) caused by the photoexcited carriers at the band edges, which obstructs the
Raman scattering pathway related to the band-edge states. Researchers from the Chinese Academy of Sciences and National Center for Nanoscience and Technology investigate this.

The group used the C-WAVE GTR for the Raman measurements.

This work paves the way to optimize the sensitivity of Raman spectroscopy by engineering carrier relaxation dynamics to enhance RRS intensity, enabling insights into electronic transitions and electron–phonon coupling in low dimensional semiconductors and related heterostructures.