Quantitative Kinematic Analysis of Jumping Crystals Presented
Crystals can jump – that’s what a team of scientists from Russia and the United Arab Emirates have discovered recently. After a systematic examination of how crystals behave in response to light, the team have presented the first quantitative kinematic analysis of jumping crystals, published in the journal Angewandte Chemie.
The crystals move thanks to a phenomenon called the ‘photosalient effect’: when irradiated by UV light, the crystals move around. The size of the crystals are micrometre or millimetre in size and of the cobalt coordination complex [Co(NH3)5(NO2)]Cl(NO3).
The effect has the crystals ‘jumping’ distances thousands of times larger than their size. According to the scientists, this happens because the irradiation process breaks the bond between the nitrite ligand (NO2) and the central cobalt ion.
As a result, the ligand ends up rotating in order to use one of its oxygen atoms to bind to the cobalt, resulting in a strain in the crystal and forcing it to jump and fracture, and sometimes explode.
The scientists used a microscope-mounted high-speed camera to capture the phenomenon. They observed that the distance covered by the crystal’s movement depends on how long it is exposed to irradiation and how intense the light is.
They also found that there is a lag stage between exposure and movement, as the stress caused by the irradiation builds up. The findings could be useful for the design of materials and technical components.