Figure 2.

Long‐term irradiation of degassed (open symbols) or non‐degassed (crossed symbols) CH₃CN‐solutions of 1 (red), 2 (blue, each 4×10⁻⁵  m, 25 °C) with a 1000 W continuum lamp using bandpass‐filters (313 nm: circles, 405 nm: squares). The decay of normalized absorption at the band maximum of the closed isomer (1: 608 nm, 2: 582 nm) illustrates the diminishing concentration of diarylethene and increasing amount of byproduct. The lines serve as guide to the eye only.