Fullerene C$_{60}$ immobilized in polymethylmethacrylate film as an optical temperature sensing material

dark prior to use. The thickness of the films was determined by the use of a micron-sensitive calliper. The thickness of the prepared film was c.a. 50 μm. The fluorescence spectrum of the C60 film was measured using a Shimadzu RF-5300PC spectrofluorophotometer with a 150 W Xenon lamp as the excitation light source. The excitation and emission bandpasses were 10 and 5.0 nm, respectively. The sample film was mounted at a 45o angle to minimize light scattering from the sample and substrate. The temperature (260-373 K) was controlled using an Oxford Instrument Optistat-DN cryostat system. All the experiments were carried out under ambient condition.