AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Thursday Sessions
       Session NS+NANO6-ThM

Paper NS+NANO6-ThM11
Cluster Size Effect Observed for Gold and Silver Sulfide Nanoparticles Synthesized by Sol-Gel Technique as Studied by X-ray Photoelectron Spectroscopy

Thursday, October 5, 2000, 11:40 am, Room 302

Session: Nanostructured Materials
Presenter: S. Shukla, University of Central Florida
Authors: S. Shukla, University of Central Florida
S. Seal, University of Central Florida
S. Mishra, University of Memphis
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Gold and Silver Sulfide nanoparticles have been successfully synthesized by a novel sol-gel technique. AFM analysis indicates the formation of @<=@12-14 nm and 40-60 nm size Au nanoparticles; while TEM and AFM analysis indicate the formation of Ag@sub 2@S nanoparticles with average size of 26 nm (with broad size distribution ranging from 2.5 nm to 56 nm) and 200-300 nm, for respective H@sub 2@S/not heated and H@sub 2@S/heated samples. XPS analysis of H@sub 2@S/not heated sample, for Au nanoparticles, reveals that the core-level Au 4f@sub 7/2@ B.E. is shifted by +0.3 eV (with increase in the FWHM of 0.2 eV) relative to the bulk value of 84.0 eV. The shift is interpreted in terms of the changes in the electronic structure due to finite cluster size and creation of +ve charge over the surface of cluster during the photoemission process itself. The electronic structure of Au nanoparticles (or clusters) produced via present sol-gel technique is compared with that of Au clusters deposited by evaporation method described in the literature. XPS analysis of Ag@sub 2@S nano and powder particles suggests that the Ag 3d@sub 5/2@ B.E. level is a function of particle size distribution. Moreover, in both the systems, -ve shift in the core-level B.E. is observed, for H@sub 2@S/heated sample, which is attributed to the small size of the particles and their faceted nature. Suitability of the present method to produce silver sulfide ion-selective electrodes is demonstrated by depositing Ag@sub 2@S nanoparticles on the graphite rod and testing its response function.