The absorbed light intensity / *+$ (1 ,--) during E→Z and Z→E isomerization at the corresponding irradiation wavelengths and initial concentration CE0 of the E-isomer was determined using Eq. 5. The value obtained was similar to that resulting from the use of a Thorlabs PM16-140 -USB Power Meter (Integrating Sphere Sensor, FC Fiber Adapter, Si, 350 -1100 nm, 500 mW Max):