Change in the luminescence intensity, at 470 nm, of a typical, UV-activated ITS
oxygen indicator film as a function of time, under an ambient atmosphere (solid
line) and when exposed to air (broken line), having been first UV-activated under
vacuum. Each film was fully
photobleached, using UVA irradiation, before being allowed to recover in
air. The insert diagram is a first-order
plot, over one half life, derived from the data in the main diagram.
