Similar behaviour was found for cotton cellulose, for cellulose immersed into water and for microcrystalline cellulose. The emission recovery was less efficient for samples immersed into deaerated water. Thus, a chromophore regeneration mechanism not dependent on the availability of oxygen is supported. Samples of microcrystalline cellulose show a considerably faster emission recovery than cotton cellulose.
Cellulose treated with ozone shows a more pronounced photochromism than untreated cellulose.
Thus, carbonyl and lactone type structures are likely to be involved in the rearrangements.