article · 18/09/2019
Raman Tweezers Microspectroscopy of Functionalized 4.2-nm Diameter CdSe Nanocrystals in Water Reveals Changed Ligand Vibrational Modes by a Metal Cation
Résumé
We demonstrated the possibility of acquiring Raman spectra of colloidal quantum dots (QDs) at low concentration in water with a size as small as 2.5 nm in diameter using Raman tweezers microspectroscopy. We measured the spectra of CdSe QDs capped with thioglycerol and with l-cysteine. This technique was applied to probe the interaction between Co2+ and Cys–CdSe QDs whose fluorescence emission is quenched in the presence of this metal cation. The quenching mechanism was so far hypothetical. The Raman spectra of Cys–CdSe QDs recorded in the absence and in the presence of Co2+ demonstrated the binding of Co2+ cations to the carboxylate groups of the l-cysteine ligand grafted on the surface of the 4.2 nm CdSe QDs. The frequency of modes for the grafted ligand is changed with respect to the free ligand in solution. Considering the vibrational coupling between the excitonic state and the ligand, we inferred that the binding of a metal cation to the grafted ligand modifies this coupling, so that exciton relaxation through crystal defects is favored. This result rationalizes the fluorescence quenching observed during the metal cation–QD interaction.
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Mrad, R., Kruglik, S.-G., Ben Brahim, N., Ben Chaabane, R., & Negrerie, M. (2019). Raman Tweezers Microspectroscopy of Functionalized 4.2-nm Diameter CdSe Nanocrystals in Water Reveals Changed Ligand Vibrational Modes by a Metal Cation. Journal of Physical Chemistry C, 123(40), 24912-24918. https://doi.org/10.1021/acs.jpcc.9b06756@article{Mrad2019_312,
author = {Mrad, R. and Kruglik, S. G. and Ben Brahim, N. and Ben Chaabane, R. and Negrerie, M.},
year = {2019},
month = {9},
title = {Raman Tweezers Microspectroscopy of Functionalized 4.2-nm Diameter CdSe Nanocrystals in Water Reveals Changed Ligand Vibrational Modes by a Metal Cation},
journal = {Journal of Physical Chemistry C},
volume = {123},
number = {40},
pages = {24912-24918},
abstract = {We demonstrated the possibility of acquiring Raman spectra of colloidal quantum dots (QDs) at low concentration in water with a size as small as 2.5 nm in diameter using Raman tweezers microspectroscopy. We measured the spectra of CdSe QDs capped with thioglycerol and with l-cysteine. This technique was applied to probe the interaction between Co2+ and Cys–CdSe QDs whose fluorescence emission is quenched in the presence of this metal cation. The quenching mechanism was so far hypothetical. The Raman spectra of Cys–CdSe QDs recorded in the absence and in the presence of Co2+ demonstrated the binding of Co2+ cations to the carboxylate groups of the l-cysteine ligand grafted on the surface of the 4.2 nm CdSe QDs. The frequency of modes for the grafted ligand is changed with respect to the free ligand in solution. Considering the vibrational coupling between the excitonic state and the ligand, we inferred that the binding of a metal cation to the grafted ligand modifies this coupling, so that exciton relaxation through crystal defects is favored. This result rationalizes the fluorescence quenching observed during the metal cation–QD interaction.},
url = {https://pubs.acs.org/doi/10.1021/acs.jpcc.9b06756},
doi = {10.1021/acs.jpcc.9b06756},
}TY - JOUR
AU - Mrad, R.
AU - Kruglik, S. G.
AU - Ben Brahim, N.
AU - Ben Chaabane, R.
AU - Negrerie, M.
PY - 2019
DA - 2019/09/18
TI - Raman Tweezers Microspectroscopy of Functionalized 4.2-nm Diameter CdSe Nanocrystals in Water Reveals Changed Ligand Vibrational Modes by a Metal Cation
JO - Journal of Physical Chemistry C
VL - 123
IS - 40
AB - We demonstrated the possibility of acquiring Raman spectra of colloidal quantum dots (QDs) at low concentration in water with a size as small as 2.5 nm in diameter using Raman tweezers microspectroscopy. We measured the spectra of CdSe QDs capped with thioglycerol and with l-cysteine. This technique was applied to probe the interaction between Co2+ and Cys–CdSe QDs whose fluorescence emission is quenched in the presence of this metal cation. The quenching mechanism was so far hypothetical. The Raman spectra of Cys–CdSe QDs recorded in the absence and in the presence of Co2+ demonstrated the binding of Co2+ cations to the carboxylate groups of the l-cysteine ligand grafted on the surface of the 4.2 nm CdSe QDs. The frequency of modes for the grafted ligand is changed with respect to the free ligand in solution. Considering the vibrational coupling between the excitonic state and the ligand, we inferred that the binding of a metal cation to the grafted ligand modifies this coupling, so that exciton relaxation through crystal defects is favored. This result rationalizes the fluorescence quenching observed during the metal cation–QD interaction.
SP - 24912
EP - 24918
DO - 10.1021/acs.jpcc.9b06756
UR - https://pubs.acs.org/doi/10.1021/acs.jpcc.9b06756
ER -