Identification of individual and few layers of WS2 using Raman Spectroscopy

• DOI: 10.1038/srep01755
• Publication Date: 2013-04-30T09:01:10Z
• Authors: Ayse Berkdemir; Humberto R. Gutié...; Andrés R. Botello...; Néstor Perea-López; Ana Laura Elías; Chen-Ing Chia; Bei Wang; Vincent H. Crespi; Florentino López-...; Jean-Christophe C...; Humberto Terrones; Mauricio Terrones
• Keywords: Fermi's golden rule; Excitation wavelength; Lattice (music)

The Raman scattering of single- and few-layered WS2 is studied as a function the number S-W-S layers excitation wavelength in visible range (488, 514 647 nm). For three wavelengths used this study, frequency A1g(Γ) phonon mode monotonically decreases with layers. single-layer WS2, 514.5 nm laser generates second-order resonance involving longitudinal acoustic (LA(M)). This results from coupling between electronic band structure lattice vibrations. First-principles calculations were to determine structures bulk WS2. reduced intensity 2LA was then computed, wavelength, fourth-order Fermi golden rule. Our observations establish an unambiguous nondestructive fingerprint for identifying films.