Table of Contents
Physics Research International
Volume 2012 (2012), Article ID 975948, 11 pages
http://dx.doi.org/10.1155/2012/975948
Research Article

Quantitative Comparison of Five Different Photosensitizers for Use in a Photopolymer

1School of Electrical, Electronic, and Communications Engineering, Communications and Optoelectronic Research Centre, The SFI-Strategic Research Cluster in Solar Energy Conversion, College of Engineering and Architecture, University College Dublin, Belfield, Dublin 4, Ireland
2Department of Computer Science, NUIM, Maynooth, Kildare, Ireland
3Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apartado 99, 03080 Alicante, Spain

Received 2 May 2012; Accepted 19 July 2012

Academic Editor: Yasuo Tomita

Copyright © 2012 Yue Qi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Several studies of the time varying photon absorption effects, which occur during the photoinitiation process involving in photopolymer materials, have been presented. Three primary mechanisms have been identified: (i) the dye absorption, (ii) recovery, and (iii) bleaching. Based on an analysis of these mechanisms, the production of primary radicals can be physically described and modelled. In free radical photopolymerization systems, the excited dye molecules induce the production of the primary radicals, 𝑅, which are key in determining how many monomers are polymerized. This, in turn, is closely related to the refractive index modulation formed during holographic recording. In this paper, to avoid the complexities involved in estimating the rate constant of intersystem crossing, 𝑘𝑠𝑡, in going from the excited singlet state dye to the excited triplet state dye, we introduce two rates, 𝑘𝑎𝑆 and 𝑘𝑎𝑇 these are the proposed rate constants of photon absorption in going from the ground state to the singlet and triplet states, respectively. Using the resulting model, four kinds of Xanthene dyes: Erythrosin B; Eosin Y; Phloxine B, Rose Bengal, and one Thiazine dye: Methylene Blue, are experimentally characterised for use in an AA/PVA photopolymer.