Testing the diffusion hypothesis as a mechanism of self-healing in Disperse orange 11 doped in PMMA

TL;DR

This study investigates the mechanism behind reversible photodegradation in Disperse Orange 11 doped in PMMA, providing evidence that it is not caused by dye diffusion but by formation of a damaged species.

Contribution

The paper demonstrates that reversible photodegradation in this system is not due to dye diffusion, challenging a common assumption and proposing an alternative mechanism.

Findings

Diffusion is not responsible for reversible photodegradation.

Spectroscopic data show an isobestic point indicating a damaged species.

Numerical diffusion models do not match experimental results.

Abstract

In this work, we show that reversible photodegradation of Disperse Orange 11 doped in PMMA is not due to dye diffusion - a common phenomenon observed in many dye-doped polymers. The change in linear absorbance due to photodegradation of the material shows an isobestic point, which is consistent with the formation of a quasi-stable damaged species. Spatially-resolved amplified spontaneous emission and fluorescence, both related to the population density, are measured by scanning the pump beam over a burn mark. A numerical model of the time evolution of the population density due to diffusion is inconsistent with the experimental data suggesting that diffusion is not responsible.