Change in the absorbance, at 600 nm, of a typical UV-activated ITS oxygen
indicator film as a function of time, under an ambient atmosphere (solid line)
and an ITS film UV-activated under vacuum and subsequently exposed to air (broken line). Each film was fully photobleached, using UVA light,
before being allowed to recover. The
insert diagram is a first-order plot (natural log of the change in the
absorbance, that is, ln (Abs), at 600 nm versus time), over
one half life, derived from the data in the main diagram. The rate
constants for this recovery step are given in Table 1.
