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 30.03.2009   Карта сайта     Language По-русски По-английски
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30.03.2009

Efficient Hg and Ag ion detection with luminescent PbS quantum dots grown in poly vinyl alcohol and capped with mercaptoethanol






Naresh Babu Pendyalaa and K.S.R. Koteswara RaoCorresponding Author Contact Information, a, E-mail The Corresponding Author






aDepartment of Physics, Indian Institute of Science, Bangalore 560012, India






Received 23 June 2008; 


revised 31 December 2008; 


accepted 16 January 2009. 


Available online 28 January 2009.






Abstract


PbS quantum dots capped with mercaptoethanol (C2H5OSH) have been synthesized in poly vinyl alcohol and used to investigate their photoluminescence (PL) response to various ions such as zinc (Zn), cadmium (Cd), mercury (Hg), silver (Ag), copper (Cu), iron (Fe), manganese (Mn), cobalt (Co), chromium (Cr) and nickel (Ni). The enhancement in the PL intensity was observed with specific ions namely Zn, Cd, Hg and Ag. Among these four ions, the PL response to Hg and Ag even at sub-micro-molar concentrations was quite high, compared to that of Zn and Cd. It was observed that the change in Pb and S molar ratio has profound effect on the sensitivity of these ions. These results indicate that the sensitivity of these QDs could be fine-tuned by controlling the S concentration at the surface. Contrary to the above, Cu quenched the photoluminescence. In Cd based QDs related ion probing, Hg and Cu was found to have quenching properties, however, our PbS QDs have quenching property only for Cu ions. This was attributed to the formation HgS at the surface that has bandgap higher than PbS. Another interesting property of PbS in PVA observed is photo-brightening mechanism due to the curing of the polymer with laser. However, the presence of excess ions at the surface changes its property to photo-darkening/brightening that depends on the direction of carrier transfer mechanism (from QDs to the surface adsorbed metal ions or vice-versa), which is an interesting feature for metal ion detectivity.





Keywords: PbS QDs; Photoluminescence; Ion probes; Enhancement; Quenching





Article Outline



1. Introduction
2. Experimental

2.1. Reagent and apparatus
2.2. Synthesis of mercaptoethanol-capped PbS QDs
2.3. Fluorescent titration experiments

3. Results and discussion
4. Conclusions
Acknowledgements
References





























Corresponding Author Contact InformationCorresponding author. Tel.: +91 80 22932866; fax: +91 80 23602602.




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А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

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