Please use this identifier to cite or link to this item:
|Title:||Observation of room-temperature high-energy resonant excitonic effects in graphene||Authors:||Santoso, I.
|Issue Date:||10-Aug-2011||Citation:||Santoso, I., Gogoi, P.K., Su, H.B., Huang, H., Lu, Y., Qi, D., Chen, W., Majidi, M.A., Feng, Y.P., Wee, A.T.S., Loh, K.P., Venkatesan, T., Saichu, R.P., Goos, A., Kotlov, A., Rübhausen, M., Rusydi, A. (2011-08-10). Observation of room-temperature high-energy resonant excitonic effects in graphene. Physical Review B - Condensed Matter and Materials Physics 84 (8) : -. ScholarBank@NUS Repository. https://doi.org/10.1103/PhysRevB.84.081403||Abstract:||Using a combination of ultraviolet-vacuum ultraviolet reflectivity and spectroscopic ellipsometry, we observe a resonant exciton at an unusually high energy of 6.3 eV in epitaxial graphene. Surprisingly, the resonant exciton occurs at room temperature and for a very large number of graphene layers N≈75, thus suggesting a poor screening in graphene. The optical conductivity (σ1) of a resonant exciton scales linearly with the number of graphene layers (up to at least 8 layers), implying the quantum character of electrons in graphene. Furthermore, a prominent excitation at 5.4 eV, which is a mixture of interband transitions from π to π* at the M point and a π plasmonic excitation, is observed. In contrast, for graphite the resonant exciton is not observable but strong interband transitions are seen instead. Supported by theoretical calculations, for N≤ 28 the σ1 is dominated by the resonant exciton, while for N> 28 it is a mixture between exitonic and interband transitions. The latter is characteristic for graphite, indicating a crossover in the electronic structure. Our study shows that important elementary excitations in graphene occur at high binding energies and elucidate the differences in the way electrons interact in graphene and graphite. © 2011 American Physical Society.||Source Title:||Physical Review B - Condensed Matter and Materials Physics||URI:||http://scholarbank.nus.edu.sg/handle/10635/82797||ISSN:||10980121||DOI:||10.1103/PhysRevB.84.081403|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Jun 29, 2022
WEB OF SCIENCETM
checked on Jun 29, 2022
checked on Jun 23, 2022
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.