biostudies-literatureLuo WBoston UniversityOffice of ScienceNational Science Foundation482-489https://www.ebi.ac.uk/biostudies/studies/S-EPMC9706783biostudies-literatureUnknown2(6)The group-10 noble-metal dichalcogenides have recently emerged as a promising group of two-dimensional materials due to their unique crystal structures and fascinating physical properties. In this work, the resonance enhancement of the interlayer breathing mode (B1) and intralayer A_g ¹ and A_g ³ modes in atomically thin pentagonal PdSe₂ were studied using angle-resolved polarized Raman spectroscopy with 13 excitation wavelengths. Under the excitation energies of 2.33, 2.38, and 2.41 eV, the Raman intensities of both the low-frequency breathing mode B1 and high-frequency mode A_g ¹ of all the thicknesses are the strongest when the incident polarization is parallel to the <i>a</i> axis of PdSe₂, serving as a fast identification of the crystal orientation of few-layer PdSe₂. We demonstrated that the intensities of B1, A_g ¹, and A_g ³ modes are the strongest with the excitation energies between 2.18 and 2.38 eV when the incident polarization is parallel to PdSe₂ <i>a</i> axis, which arises from the resonance enhancement caused by the absorption. Our investigation reveals the underlying interplay of the anisotropic electron-phonon and electron-photon interactions in the Raman scattering process of atomically thin PdSe₂. It paves the way for future applications on PdSe₂-based optoelectronics.ACS physical chemistry AuExcitation-Dependent Anisotropic Raman Response of Atomically Thin Pentagonal PdSe₂.PMC9706783DE-AC05-00OR227251945364Mao NXiao KLing XLuo WLiang LOyedele ADPuretzky AfalseExcitation-Dependent Anisotropic Raman Response of Atomically Thin Pentagonal PdSe₂.The group-10 noble-metal dichalcogenides have recently emerged as a promising group of two-dimensional materials due to their unique crystal structures and fascinating physical properties. In this work, the resonance enhancement of the interlayer breathing mode (B1) and intralayer A_g ¹ and A_g ³ modes in atomically thin pentagonal PdSe₂ were studied using angle-resolved polarized Raman spectroscopy with 13 excitation wavelengths. Under the excitation energies of 2.33, 2.38, and 2.41 eV, the Raman intensities of both the low-frequency breathing mode B1 and high-frequency mode A_g ¹ of all the thicknesses are the strongest when the incident polarization is parallel to the <i>a</i> axis of PdSe₂, serving as a fast identification of the crystal orientation of few-layer PdSe₂. We demonstrated that the intensities of B1, A_g ¹, and A_g ³ modes are the strongest with the excitation energies between 2.18 and 2.38 eV when the incident polarization is parallel to PdSe₂ <i>a</i> axis, which arises from the resonance enhancement caused by the absorption. Our investigation reveals the underlying interplay of the anisotropic electron-phonon and electron-photon interactions in the Raman scattering process of atomically thin PdSe₂. It paves the way for future applications on PdSe₂-based optoelectronics.2022-01-01T00:00:00Z2022 Nov2026-03-27T16:13:04.058Z2025-02-19T04:34:06.09ZS-EPMC97067833646583610.1021/acsphyschemau.2c00007