Excited Excitonic States in 1L, 2L, 3L, and Bulk WSe2 Observed by Resonant Raman Spectroscopy
Del Corro, Elena (Universidade Federal de Minas Gerais. Departamento de Física)
Terrones, Humberto (Rensselaer Polytechnic Institute)
Elias, Ana Laura (The Pennsylvania State University. Department of Physics)
Fantini, Cristiano (Universidade Federal de Minas Gerais. Departamento de Física)
Feng, Simin (The Pennsylvania State University. Department of Physics)
Nguyen, Minh An (The Pennsylvania State University. Department of Chemistry)
Mallouk, Thomas E. (The Pennsylvania State University. Department of Chemistry)
Terrones, Mauricio (The Pennsylvania State University. Department of Physics)
Pimenta, Marcos A. (Universidade Federal de Minas Gerais. Departamento de Física)

Date:	2014
Abstract:	Resonant Raman spectroscopy (RRS) is a very useful tool to study physical properties of materials since it provides information about excitons and their coupling with phonons. We present in this work a RRS study of samples of WSe with one, two, and three layers (1L, 2L, and 3L), as well as bulk 2H-WSe, using up to 20 different laser lines covering the visible range. The first- and second-order Raman features exhibit different resonant behavior, in agreement with the double (and triple) resonance mechanism(s). From the laser energy dependence of the Raman intensities (Raman excitation profile, or REP), we obtained the energies of the excited excitonic states and their dependence with the number of atomic layers. Our results show that Raman enhancement is much stronger for the excited A' and B' states, and this result is ascribed to the different exciton-phonon coupling with fundamental and excited excitonic states.
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Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Published in:	ACS nano, Vol. 8, Issue 9 (August 2014) , p. 9629-9635, ISSN 1936-086X

DOI: 10.1021/nn504088g

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