Fig. 1. Solid-state sample of OSO embedded in PDMS (left) and the commonly studied solution of OSO in DCM in a cuvette (right).

Fig. 2. Extinction spectra ε(ν)=α(ν)/c of OSO embedded in PDMS (left) compared to a solution of OSO in DCM (right), modeled by a sum of Voigt and Gaussian profiles [22].

Fig. 3. (a) Extinction characteristics of the OSO-PDMS sample as a function of time when exposed to a white-light source at room temperature. (b) Characteristics of (a) for the experimental data (o) at λ=500  nm and the fit according to Eq. (1) (black line).

Fig. 4. Double population-thermal relaxation-cycle of the OSO-PDMS sample at λ=500  nm: (a) Optical population of the molecules from the ground state into the metastable structural isomers with (b) subsequent thermal relaxation back to the ground state. (c) Afterward, the molecules are transferred back to the metastable states by a second optical excitation. The following thermal relaxation to the ground state is shown in part (d), indicating a reproducible excitation cycle.

Fig. 5. (a) Spatial homogeneity of the extinction coefficient ε at λ=400  nm in top view of a 3D OSO-PDMS sample and related to its average value. (b) ε at λ=500  nm after illumination of a dot with a diameter of 2.6 mm.

Fig. 6. (a) Emblem of the Osnabrück University being illuminated in an OSO-PDMS sample. (b) Transmitted light intensity for the wavelengths λ=(632±10)  nm, λ=(532±10)  nm, and λ=(488±10)  nm at the dashed line in (a).

Fig. 7. Structures of a 1951 USAF target are transferred into an OSO-PDMS sample and analyzed by a microscope.