UP chemists make light work

UP master’s student Ané Kritzinger has built an optical tweezing system with an integrated fluorescence microscope for the detection of water pollutants at extremely low concentrations. The trap has been used with collaborators to demonstrate a hidden property in light that remains unchanged even when it passes through turbulence. “Like a rock rolling down a hill has momentum, so too does light, but one cannot observe this in our everyday lives,” says Prof Patricia Forbes of UP’s Environmental Monitoring and Sensing Research Group. “In the microscopic world, however, we can use this momentum of light to trap (hold) particles and move them around in a controlled way. We can use a laser to ‘hold’ a specific particle of interest so we can analyse it, in this case by observing the fluorescence of the particle.”