We present the formation of self-assembly of haematite particles induced by an optically trapped and heated Upconverting Particle [1]. Individual haematite particles in water form a dispersion
and have very high refractive index and absorption, making them extremely difficult to optically trap. The Upconversion particles (UCPs) are well known for their ability to convert low-energy
photons to high-energy photons through multiphoton transfers. A single Lanthanide doped Upconversion particle (NaYF4:Yb3+, Er3+) was trapped with a 975 nm laser in the proximity of an
air-water interface. Due to its enormous absorption at 975nm light and low upconversion
efficiency, it generates local heating, which gives rise to convection currents around the particle
and brings the haematite particle to aggregate near the trapped UCP and initiate the process for
the formation of self-assembly.
Refrences:-
1. Goswami, J., Nalupurackal, G., Lokesh, M., Roy, S., Chakraborty, S., Bhattacharya, A., ... & Roy, B. (2023).
Formation of Two-Dimensional Magnetically Responsive Clusters Using Hematite Particles Self-Assembled via
Particle-Induced Heating at an Interface. The Journal of Physical Chemistry B.