Figure Surface reflectivity vs wavelength plots of 1 as a function of temperature recorded in dark in cooling mode from 350 K -10 K (left) and Thermal evolution of absolute reflectivity signal of 1 plotted at 650 nm in cooling mode in dark (300 -10 K, at 4 K min -1 , red), and heating mode (10 -300 K, at 4 K min -1 , blue), during white light irradiation (0.5 mWcm -2 , at 10 K, green line) and in heating mode after light irradiation (10 -300 K, at 0.5 K min -1 , green circles).