Nanoparticle metrology in sol-gels using multiphoton excited fluorescence

Karolin, J. and Geddes, C.D. and Wynne, Klaas and Birch, D.J.S. (2001) Nanoparticle metrology in sol-gels using multiphoton excited fluorescence. Measurement Science and Technology, 13 (1). pp. 21-27. ISSN 0957-0233

Abstract

We have developed a method of measuring the growth of nanoparticles during sol-gel glass formation based on labelling the particle with a fluorescent dye and determining the multiphoton excited decay of fluorescence anisotropy due to Brownian rotation. Multiphoton excitation is shown to give a higher dynamic range of measurement than one-photon excitation. We illustrate the sub-nanometre resolution and stability of our approach by detecting a 0.8-1.1 nm silica particle hydrodynamic mean radius increase in a tetramethylorthosilicate sol at pH 2.3 labelled with rhodamine 6G and observed over ≈4 weeks and also with a stable silica colloid of radius 6 nm, pH 8.9, labelled with a 6-methoxyquinoline-type dye.

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