  We use amplified spontaneous emission (ASE) and linear absorption
spectroscopy to study the mechanisms of reversible photodegradation of
1-amino-2-methylanthraquinone (disperse orange 11-DO11) in solid poly(methyl
methacrylate). Measurements as a function of intensity, concentration, and time
suggest that ASE originates in a state (be it a tautomer or a vibronic level)
that can form a dimer or some other aggregate upon relaxation, which through
fluorescence quenching leads to degradation of the ASE signal. Whatever the
degradation route, a high concentration of DO11 is required and the polymer
plays a key role in the process of opening a new reversible degradation pathway
that is not available at lower concentrations or in liquid solutions. We
construct an energy level diagram that describes all measured quantities in the
decay and recovery processes and propose a hypothesis of the nature of the
associated states.
