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Fabrication and Atomic Force Microscopy Characterization of Molecular Composites of Fullerenes in Aerogel Matrix for Optical LimitingAn optical limiter is a device which exhibits a decrease in the transmittance in a material with an increase in intensity of light. Sol-gel techniques offer many advantages in the fabrication of materials. These materials possess many desirable properties for nonlinear optical (NLO) device applications which include transparency, high thermal and chemical stabilities, very low refractive index and dielectric constants. C60 shows a higher excited state absorption cross section than the ground state absorption cross section over the complete visible spectrum, and the spectrum of the excited state absorption of C60 has the same general shape as the ground state absorption. This fact suggests that fullerenes are ideal optical limiting materials. Aerogels are fabricated by sol-gel processing. One of the key issues is the dispersion of fullerenes into small and uniform pores of silica aerogel host matrices. The aerogel network was characterized by Raman spectroscopy. Atomic force microscopy is a technique with many advantages to characterize the aerogel materials. The morphology of the cleaved surface for a C60/aerogel sample shows that there are long paralleled shaped stripes with 20-30 nm in width and about 500 nm in length on the cleaved surface. The cleaved surface also was etched by 5% HF solution for one minutes, and it became smoother after HF etching. The main feature in on the surface is the spherical particles with the size of few nanometers, and no aggregated fullerenes appear. The fullerenes are well dispersed in the aerogel matrices.
Document ID
20000032330
Acquisition Source
Headquarters
Document Type
Conference Paper
Authors
Lu, W. J .
(Fisk Univ. Nashville, TN United States)
Sunkara, H. B.
(Du Pont de Nemours (E. I.) and Co. Wilmington, DE United States)
Shi, D.
(Fisk Univ. Nashville, TN United States)
Morgan, S. H.
(Fisk Univ. Nashville, TN United States)
Penn, B.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Frazier, D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Collins, W. E.
(Fisk Univ. Nashville, TN United States)
Date Acquired
August 19, 2013
Publication Date
February 22, 1998
Publication Information
Publication: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education
Volume: 2 and 3
Subject Category
Atomic And Molecular Physics
Report/Patent Number
98URC164
Funding Number(s)
CONTRACT_GRANT: NAGW-2925
CONTRACT_GRANT: NAG3-1430
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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