Detection of photon emission during crack propagation in silica glass by fast time-resolved measurement

Fast time-resolved measurement was carried out to detect photon emission (PE) during crack propagation in silica glass. The specimen was fractured by three-point bending at room temperature under 10 ^-4 Pa. The top and bottom surfaces of the specimen were coated with Au. Resistance of those surfaces was monitored to detect crack propagation in the specimen. Simultaneously, the PE was detected with photomultiplier tube. The PE around 650 nm increased and then gradually decreased during the crack propagation, while the strong the PE around 450 nm was observed at the beginning of the crack propagation. Moreover, both of the emissions started just before the onset of the crack propagation. It might be due to micro-cracks leading to a main crack propagation. The result suggests that a fracture precursor can be detected by monitoring the PE.