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Proceedings Paper

Quantum yield of conversion of the dental photoinitiator camphorquinone
Author(s): Yin-Chu Chen; Jack L. Ferracane; Scott A. Prahl
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Paper Abstract

The primary absorber in dental resins is the photoinitiators, which start the photo polymerization process. We studied the quantum yield of conversion of camphorquinone (CQ), a blue light photoinitiator, using 3M FreeLight LED lamp as the light curing unit. The molar extinction coefficient, ε469, of CQ was measured to be 46±2 cm-1/(mol/L) at 469 nm. The absorption coefficient change to the radiant exposure was measured at three different irradiances. The relationship between the CQ absorption coefficient and curing lamp radiant exposure was the same for different irradiances and fit an exponential function: μa469(H)= μao exp(-H/Hthreshold), where μao is 4.46±0.05 cm-1, and Hthreshold=43±4 J/cm2. Combining this exponential relationship with CQ molar extinction coefficient and the absorbed photon energy (i.e., the product of the radiant exposure with the absorption coefficient), we plotted CQ concentration [number of molecules/cm3] as a function of the accumulated absorbed photons per volume. The slope of the relationship is the quantum yield of the CQ conversion. Therefore, in our formulation (0.7 w% CQ with reducing agents 0.35 w% DMAEMA and 0.05 w% BHT) the quantum yield was solved to be 0.07±0.01 CQ conversion per absorbed photon.

Paper Details

Date Published: 22 June 2005
PDF: 11 pages
Proc. SPIE 5771, Saratov Fall Meeting 2004: Optical Technologies in Biophysics and Medicine VI, (22 June 2005); doi: 10.1117/12.634627
Show Author Affiliations
Yin-Chu Chen, Oregon Health & Science Univ. (United States)
Jack L. Ferracane, Oregon Health & Science Univ. (United States)
Scott A. Prahl, Oregon Health & Science Univ. (United States)

Published in SPIE Proceedings Vol. 5771:
Saratov Fall Meeting 2004: Optical Technologies in Biophysics and Medicine VI
Valery V. Tuchin, Editor(s)

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