Significantly increased Raman enhancement enabled by hot-electron-injection-induced synergistic resonances on anisotropic ReS₂ films

Abstract

Two-dimensional (2D) materials are an excellent platform for surface-enhanced Raman spectroscopy (SERS). However, a poor detection sensitivity hinders their practical application. Exciton resonance (µex) can improve SERS significantly by lending...

Dynamic repulsive interaction enables an asymmetric electron–phonon coupling for improving Raman scattering

“…T@Td-ReS 2 , was mechanically exfoliated into thinner layer films. 23 Two new peaks located at 122 cm À1 and 129 cm À1 justified the introduction of the T phase in ReS 2 , as shown in Fig. S1 in the ESI.…”

“…In addition, our previous works indicate that the Raman enhancement of the probe molecules is anisotropic due to the angular dependence of the charge distributions on T@Td-ReS 2 . 23 Herein, angle-resolved polarized Raman spectra of T@Td-ReS 2 and R6G were measured when the polarization angle of the laser is rotated. As shown in Fig.…”

“…S9 in the ESI, † one order of magnitude superior to 1 Â 10 À9 M on pristine T@Td-ReS 2 . 23 Because the insulating hBN layer can totally block the charge transfer between graphene and T@Td-ReS 2 , the improved SERS performance is attributed to the Coulomb interaction between graphene and T@Td-ReS 2 . The introduction of the insulating hBN layer reduces the electric field at the interface between graphene and T@Td-ReS 2 , which results in a slightly lower sensitivity compared with T@Td-ReS 2 /G.…”

“…22 Eventually, the Raman enhancement effect can be highly improved through the dipole-dipole interactions and synergistic resonance effects in the phase-engineering ReS 2 (T@Td-ReS 2 ) films. 23 However, it is still necessary to improve the performance of the substrate further to extend its application.…”

Beyond the Charge Transfer Mechanism for 2D Materials-Assisted Surface Enhanced Raman Scattering

“…2D materials-assisted SERS works mainly through the chemical mechanism (CM), − which contributes to the enhancement by the electronic and vibrational couplings between the molecules and substrates. It not only enhances the Raman scattering intensities but also determines the overall Raman spectrum shape due to the varied enhancement factors for different phonon modes. , Experimentally, the CM enhancement factors are significantly impacted by the 2D material type, layer thicknesses, defects, doping conditions, molecule species, molecular orientations, phonon symmetries, adsorption distances, excitation wavelength, and so on. ,,,− Charge transfer is believed responsible for the CM enhancement, ,,,,, which refers to the dynamic scattering process instead of the static charge transfer between the molecules and the substrate . However, an accurate and comprehensive understanding of the enhancement mechanism is still lacking.…”