Further optical-reflectivity studies with the LED lights were carried out at 10 K by cycling a photo-excitation at 625 nm (30 min, power 16 mWcm -2 ) and second irradiation with other LEDs to explore the possibilities of photo-reversibility of 1. The most significant changes in the spectra were observed with 1050 nm LED. Accordingly, further de-excitation studies were carried out with 1050 nm LED light irradiation at 10 K, where a slightly faster drop of the absolute reflectivity data was observed. However, because of the fast relaxation time of the photo-excited state, it is difficult to totally exclude the associated thermal effect (heating due to irradiation).