biostudies-literatureJadczak JDeutsche ForschungsgemeinschaftNarodowe Centrum Nauki3986-3994https://www.ebi.ac.uk/biostudies/studies/S-EPMC10165653biostudies-literatureUnknown14(17)Germanium monosulfide with an anisotropic puckered crystalline structure has recently attracted much attention due to its unique optical and electronic properties; however, exciton-phonon interactions were only superficially elucidated. We study the resonant Raman scattering and the photoluminescence of the optically active Γ-exciton in layered GeS flakes and evaluate the exciton and phonon responses on variations in the excitation energy, laser-light and emission polarizations, temperature, and laser power. A double-resonance mechanism allows for observing Raman forbidden (dark) first- and second-order longitudinal-optical phonon modes whose symmetries and energies are moreover calculated by density functional perturbation theory. For (quasi)-resonant exciton excitation, the selection rulThe journal of physical chemistry lettersResonant Exciton Scattering Reveals Raman Forbidden Phonon Modes in Layered GeS.PMC101656532020/37/B/ST3/00539TRR 160 - B4, 249492093Bryja LDebus JJadczak JAndrzejewski JHo CHfalseResonant Exciton Scattering Reveals Raman Forbidden Phonon Modes in Layered GeS.Germanium monosulfide with an anisotropic puckered crystalline structure has recently attracted much attention due to its unique optical and electronic properties; however, exciton-phonon interactions were only superficially elucidated. We study the resonant Raman scattering and the photoluminescence of the optically active Γ-exciton in layered GeS flakes and evaluate the exciton and phonon responses on variations in the excitation energy, laser-light and emission polarizations, temperature, and laser power. A double-resonance mechanism allows for observing Raman forbidden (dark) first- and second-order longitudinal-optical phonon modes whose symmetries and energies are moreover calculated by density functional perturbation theory. For (quasi)-resonant exciton excitation, the selection rul2023-01-01T00:00:00Z2023 May2025-04-04T10:19:51.386Z2025-02-19T00:12:25.158ZS-EPMC101656533708331010.1021/acs.jpclett.3c00783