Theoretical and experimental study of the bleaching of a dye in a film-polymerization process

Abstract

The quantum efficiency and the molar-absorption coefficients of different phenothiazine dyes are obtained by means of fitting the experimental data of transmittance as a function of time. An analytical expression for the intensity transmitted in a photopolymerizable holographic material is obtained, and good agreement between theory and experience is also achieved. The analysis of these parameters is of fundamental quantities in the photochemical characterization of holographic recording materials.

Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions Part I Modeling

“…The time varying absorbed intensity, I a ͑t͒ ͑Einstein/ cm 3 s͒, is given by an adaptation of the Beer-Lambert equation [10,23,24]…”

Extended model of the photoinitiation mechanisms in photopolymer materials

“…While significant progress has been made in the work presented here, [1][2][3][4][5][6][7][8]11,13,14 much remains to be done. Most obviously, the process of intersystem crossing must be more physically modeled and the fraction parameter ⌿ must be eliminated.…”

“…where I 0 Ј ͑Einstein/ cm 2 s͒ is the incident intensity corrected by the transmission fraction T sf , 8,14 d is the thickness of the photopolymer material layer. The fraction ⌿ differentiates between the concentration of 1 Dye * molecules generated and the concentration of the more stable ͑longer-lived͒ triplet state molecules, 3 Dye * , simultaneously generated.…”

Photopolymers for Use as Holographic Media

“…In all cases the aim has been to improve the understanding of the photo-kinetics occurring in these materials, and critically to enable accurate predictions of the generation of primary radicals. A model of photosensitiser behaviour proposed by Carretero et al [45], has recently been extended to account for: (i) photon absorption, (ii) the regeneration or recovery of absorptive photosensitiser, and (iii) photosensitiser bleaching, [46]. Using this model an expression for the time varying absorbed intensity, Ia(t) (Einstein/cm 3 s), was derived and the values of key material parameters were estimated using non-linear fits of the dye model to experimentally obtained transmission curves, [32].…”