Fracto- mechanoluminescence of sugar crystals measured with different techniques

Abstract

Here in, we report the mechanoluminescence (ML)from sugar crystals measured with different techniques. In case of statical loading technique, many ML pulses originate from sugar crystals and the total number of ML pulses increases linearly with increasing applied load. However, in case of impulsive excitation technique, the ML intensity increases linearly with increasing time, attains a saturation value and finally decreases with time. Semilog plot of ML intensity vs (t-tm)curve gives negative slope. The value of tm decreases with increasing impact velocity while it increases with the thickness of the sugar crystals. A linear relation between peak ML intensity and impact velocity has been observed in the present case where the total ML intensity initially increases linearly with impact velocity and gets saturated. The temperature has a negative effect on ML intensity. The ML intensity is found to decrease with increasing temperature. At the higher velocities, the decay is fast and it slows down at lower velocities. The pulse induced ML is a new and advanced technique in which when the sugar crystals are deformed, the ML pattern is similar to that as obtained during impulsive excitation with minor differences. At low impact pressures, fast and slow decays are found, while at high impact pressure only fast decay is witnessed. The ML intensity increases and is proportional to impact pressure for sugar crystals whereas the total ML intensity is found to be dependent of the volume of the sugar crystals.