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2014
2014
Peer-reviewed Publications |
Rogez, B., Yang, H., Le Moal, E., Lévêque-Fort, S., Boer-Duchemin, E., Yao, F., Lee, Y. - H., Zhang, Y., Wegner, D., Hildebrandt, N., Mayne, A. J., & Dujardin G. (2014). Fluorescence lifetime and blinking of individual semiconductor nanocrystals on graphene. J. Phys. Chem. C, 118, 18445–18452.
Résumé: A new class of optoelectronic nanodevices consisting of 0D semiconductor nanocrystals and 2D single graphene layers is attracting much attention. In particular, such a system may be used to investigate and control the transfer of energy and charge in low-dimensional systems. To this end, the fluorescence dynamics of individual colloidal quantum dots(QDs) on graphene are investigated on both the 10−9 to 10−8 s time scale (fluorescence lifetime) and the 1−100 s time scale(blinking statistics) in this paper. We find that (i) a nonradiative energy transfer rate of ≈5 × 10+8 s−1 is obtained from the reduced lifetimes of QDs on graphene as opposed to those on insulating substrates such as glass; (ii) QDs still exhibit fluorescence intermittency (“blinking”) on graphene; (iii) the cumulative distribution functions of the “off” times may be described by power-law statistics; (iv) QD coupling to graphene increases the time spent in the “on” state while the time spent in the “off” state remains relatively unchanged; and (v) the fluorescence emission spectrum of the QDs is practically unaltered by the QD−graphene coupling.
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Yengui, M., & Riedel, D. (2014). Cobalt adsorption on the bare Si(100)-2x1 surface at low temperature (12 K). SURFACE SCIENCE, 619(1), 10–18.
Résumé: The adsorption of Co atoms on the bare Si(100)-2×1 surface at low temperature (12 K) is performed in the low coverage regime (b 0.1monolayer). The ensuing surface is studied by means of a lowtemperature (9K) scanning tunneling microscope (STM). Several adsorption sites are described via STM topographies and differential conductance spectroscopy. Our study reveals that at low temperature (12 K), a significant fraction of the Co atoms diffuse into the surface and form the first stage reaction sites that are relevant for the silicidation mechanism of the Si(100). Furthermore, the low temperature conditions allow to describe surface Co adatoms conformations that are stabilized on the Si(100)-c(4×2) surface. Interestingly,we have observed the irreversible transformation of the symmetric pedestal site (Ps) to the under dimer site (UD) via specific STM scanning conditions. Finally, the presence of dimer vacancy lines is discussed and reveals that the activated etching process of the silicon dimer with metals can be induced at very low temperature.
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Chapitres de Livres |
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Sonnet, P., & Riedel, D. (2014). The Scanning Tunneling Microscopy of Adsorbed Molecules on Semiconductors : Some Theoretical Answers to the Experimental Observations. In Practical Aspects of Computational Chemistry III (Vol. 3, pp. 1–40). Jerzy Leszczynski; Manoj K. Shukla.
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