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2 Optica Applicata

2 2008

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Formation and structural characterization of silver nanoparticles in ormosil sol-gel films

100%

Reisfeld R. , Saraidarov T. , Levchenko V.

Optica Applicata

2008

tom Vol. 38, nr 1

83-92

Silver nanoparticles were obtained in situ in ormosil sol-gel films with attached urethane groups. Optical spectra of the silver nanoparticles in the films show red shift of absorption maximum with increasing silver concentration from 2% to 10%. In the solutions lambda max is shifted from 390 nm till 425 nm; in the films lambda max is shifted from 438 nm till 456 nm. Structural characterizations of the composite sol-gel films incorporated by silver nanocrystals have been studied by: scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersion X-rays analysis (EDAX), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and scanning transmission electron microscopy (STEM). Two types of silver nanoparticles with sizes of 1-2 nm and 20-40 nm were observed. The crystal grow process and particle sizes depend on the starting concentrations of silver ions, reaction temperature and time. The small silver particles are arranged in micro pores of the matrix, as shown from STEM images. SAED confirms the silver face-centered cubic crystal lattice.

Electrical conductivity of doped porous glasses as possible sensors for oxygen

88%

Saraidarov T. , Reisfeld R. , Elena Zigansky E. , Sashchiuk A. , Lifshitz E.

Optica Applicata

2008

tom Vol. 38, nr 1

109-117

We are proposing Rubpy complex incorporated in a number of porous sol-gel thin films as a sensor for oxygen. The principle is based on the following fact: triplet oxygen reacts with the excited states of Rubpy resulting in decay of luminescence of the complex due to triplet quenching. The decrease of fluorescence is proportional to the amount of absorbed oxygen. We discuss here several sol-gel matrices with doped by Ru(bpy)3+2 deposited as thin films on ITO conducting glass. The absorption and emission spectra of the complex, and electrical conductivity of the doped films show how the fluorescence can be excited either by optical or electronic means. The decrease of fluorescence indicates the concentration of oxygen.