Physics Colloquium - Fall 2006 - Surface-Enhanced Raman Spectroscopy to Study Adsorption of Molecules on Semi-Conductor Quantum Dots
Dept of Physics & Astronomy
University of Maine, Orono, Maine
Presents
Professor John R. Lombardi
Department of Chemistry,
City College, CUNY, New York, NY
Surface-Enhanced Raman Spectroscopy to Study Adsorption of Molecules on Semi-Conductor Quantum Dots
This research stems from a recent discovery by one of our collaborators
[i]
that surface-enhanced Raman scattering (SERS) can directly probe the adsorption of molecules on InAs/GaAs quantum-dots nanostructures grown by molecular beam epitaxy (MBE). We have since confirmed and extended that result in this laboratory by observation of enhanced Raman intensity in several molecules on self-assembled CdSe/CdZnSeMg quantum dots
[ii]
. Enhancement factors of on the order of at least 103 were observed in the former system, while in the latter they were up to 106. Surface enhancement has been observed on semiconductor nanoparticles in colloidal suspensions such as CdS
[iii]
, ZnS
[iv]
, ZnO
[v]
, and CdTe
[vi]
. These results are quite surprising, because previously such surface enhancement was observed almost exclusively on metals such as silver, copper, and gold as well as numerous alkali and transition metals. This work demonstrates that SERS presents a promising technique for the study of surface species present on semiconductor nanostructures and of interactions between the semiconductor surface and the adsorbed species.
[1]
Observation of Molecules Adsorbed on III-V Semiconductor Quantum Dots by Surface Enchanced Raman Scattering; Quagliano, L.G., J. Am. Chem. Soc., 2004, 126, 7393-7398.
[1]
SERS as sensing method for bio-molecules on MBE-grown quantum dots; Livingstone,R. L. G. Quagliano, L.G, Perez-Paz, N.; Munoz, M.; Tamargo, M.C.; Jean-Mary, F.; Lombardi, J.R., Proceedings of SPIE: Nanosensing: Materials and DevicesII, M. Saif Islam, A.K. Dutta eds., 6008-0A, 2005.
[1]
Surface Enhanced Raman Scattering on Mercaptopyridine-Capped CdS Microclusters, Y. Wang, Z. Sun., Y. Wang, H. Hu, B. Zhao, W. Xu, J.R. Lombardi, Spectrochimica Acta A., in press.
[1]
Raman Scattering Study of Molecules Adsorbed on ZnS Nanocrystals, Y. Wang, Z. Sun., Y. Wang, H. Hu, S. Jing, B. Zhao, W. Xu, C. Zhao, J.R. Lombardi, J. Raman Spectroscopy, in press.
[1]
Direct Observation of Surface-Enhanced Raman Scattering in ZnO Nanocrystals, Y. Wang, Y. Wang, J. Zhang, H. Hu, J. Zhang, B. Zhao, B. Yang, J.R. Lombardi, submitted for publication.
[1]
Mercaptopyridine Surface-Functionalized CdTe Quantum Dots: SERS Activity, Y. Wang, J. Zhang, H. Jia, M. Li, J. Zeng, B. Yang, B. Zhao, W. Xu, J.R. Lombardi, submitted for publication.
Friday, September 29, 2006
3:10 pm
Hill Auditorium, Barrows Hall
(note different location)
Refreshments will follow outside the Hill Auditorium
Back to Physics Colloquium - Fall 2006
