Radiation chemical and photophysical properties of C60 (C4H8SO3Na)n in aqueous solution: a laser flash photolysis and pulse radiolysis study

Mohan, Hari ; Palit, D. K. ; Chiang, L. Y. ; Mittal, J. P. (2001) Radiation chemical and photophysical properties of C60 (C4H8SO3Na)n in aqueous solution: a laser flash photolysis and pulse radiolysis study Fullerene Science and Technology, 9 (1). pp. 37-53. ISSN 1064-122X

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Official URL: http://www.tandfonline.com/doi/abs/10.1081/FST-100...

Related URL: http://dx.doi.org/10.1081/FST-100000163

Abstract

Optical absorption studies on aqueous solutions of C60(C4H8SO3Na)n (n = 4-6) revealed deviation from the Beer-Lambert law in the 250-350 nm region, which is assigned to the formation of solute aggregates at concentrations higher than 1 × 10-3 mol dm-3. Dynamic light scattering experiments showed aggregates with an average size of ∼100 nm. The solute has a broad weak fluorescence emission (Φƒ = 1.8 × 10-3) in the 450-650 nm region, which remained independent of solute concentration. The broad transient absorption band in the 450-900 nm region ( ε660 = 2170 dm3 mol-1 cm-1), which formed immediately on laser flash photolysis (λex = 355 nm, 35 ps), is assigned to singlet-singlet transition. It decays to a triplet excited state whose absorption is observed to depend strongly on solute concentration. In dilute solutions, an absorption band with λmax = 590 nm is seen, and at high solute concentration a broad absorption in the 500-900 nm region is observed. The eaq- reacts with the solute with a bimolecular rate constant of 1.7 × 108 dm3 mol-1 s-1 and forms weak broad absorption bands at 440, 540, 620, 870, 940, and 1020 nm. Isopropanol radicals also react with the solute with a bimolecular rate constant of 2.3 × 108 dm3 mol-1 s-1 with the formation of a transient optical absorption spectrum similar to that observed on reaction with eaq- and assigned to a solute radical anion. The H and -OH radicals react with bimolecular rate constants of 3.2 × 109 and 4.4 × 109 dm3 mol-1 s-1, respectively, and form transient absorption bands at 440, 510, and 660 nm. Based on electron transfer studies with suitable electron donor/acceptor substrates, the ranges of the reduction and oxidation potentials of the solute an estimated.

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Deposited On:28 Feb 2012 11:58
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