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Spatiially Resolved Spectra of Miicro-Crystals and Nano-Aggiregates in Doped Polymers

Published online by Cambridge University Press:  15 February 2011

Duane Birnbaum ,
Seong-Keun Kook  and
Raoul Kopelman
Duane Birnbaum
Affiliation:
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
Seong-Keun Kook
Affiliation:
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
Raoul Kopelman
Affiliation:
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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Abstract

Near-field optics techniques make it possible to by-pass the optical diffraction limit (“uncertainty principle) and attain spatial resolution of λ/50 or better. We present near-field scanning optical spectroscopy (NSOS) data on α and ß mixed micro-crystals of perylene and on various aggregates of tetracene doped into PMMA. The spatial resolution is limited by the size of the scanning photon tip and its distance from the sample. We use nanofabricated optical fiber tips (aluminum coated) that are as small as 100 nm. These can be piezoelectrically scanned close to the sample. Fluorescence spectra easily differentiate between adjoining microcrystallites of α and β perylene, giving spectra identical with those of large (>1 cm) single crystals. The apparently homogeneous molecularly doped polymer samples of tetracene/PMMA have regions that fluoresce anywhere between green and red. Thus the spatially resolved spectra are much sharper and more detailed than the broad and featureless bulk spectra. The different emission spectra are attributed to different aggregates of the tetracene guest embedded in the PMMA host

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 290: Symposium N – Dynamics in Small Confining Systems , 1992 , 227
Copyright
Copyright © Materials Research Society 1993

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