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Excitonic transitions and off-resonant optical limiting in CdS quantum dots stabilized in a synthetic glue matrix

Kurian, Pushpa Ann and Vijayan, C. and Sathiyamoorthy, K. and Sandeep, C. S. Suchand and Philip, Reji (2007) Excitonic transitions and off-resonant optical limiting in CdS quantum dots stabilized in a synthetic glue matrix. NANOSCALE RESEARCH LETTERS, 2 (11). pp. 561-568. ISSN 1931-7573 (Print) 1556-276X (Online)

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Official URL: http://www.springerlink.com/content/q4mp70611x4v20...

Abstract

Stable films containing CdS quantum dots of mean size 3.4 nm embedded in a solid host matrix are prepared using a room temperature chemical route of synthesis. CdS/synthetic glue nanocomposites are characterized using high resolution transmission electron microscopy, infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Significant blue shift from the bulk absorption edge is observed in optical absorption as well as photoacoustic spectra indicating strong quantum confinement. The exciton transitions are better resolved in photoacoustic spectroscopy compared to optical absorption spectroscopy. We assign the first four bands observed in photoacoustic spectroscopy to 1s(e)-1s(h), 1p(e)-1p(h), 1d(e)-1d(h) and 2p(e)-2p(h) transitions using a non interacting particle model. Nonlinear absorption studies are done using z-scan technique with nanosecond pulses in the off resonant regime. The origin of optical limiting is predominantly two photon absorption mechanism.

Item Type:Article
Uncontrolled Keywords:exciton; nanomaterials; optical limiting; nonlinearity; photoacoustics
Subjects:Analytical Science > Microscopy and probe methods
Material Science > Nanofabrication processes and tools
Physical Science > Photonics
ID Code:1493
Deposited By:Farnush Anwar
Deposited On:11 Dec 2008 20:10
Last Modified:15 Jan 2009 10:54

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