See that tiny green pinprick of light? That's a speck of diamond dust trapped in the grip of a laser beam. And with its help, researchers hope to better understand the border-world between macro and quantum physics.
The team, led by University of Rochester assistant professor of optics, Nick Vamivakas, has submitted a paper for publication to the journal Optics Letters describing how they were able to successfully capture, levitate, and hold diamond nanoparticles as small as 100nm indefinitely as well as incite the crystals to emit photons at varying wavelengths.
Researchers used laser trapping techniques wherein a highly concentrated laser beam exerts an attractive or repulsive force against a dielectric nanoparticle. And while science has been using so-called optical tweezers for some time, this is the first experiment to successfully pick up diamonds. And according to the U of Rochester press release:
The light emitted by the nanodiamonds is due to photoluminescence. The defects inside the nanodiamonds absorb photons from the second laser — not the one that is trapping the diamonds — which excites the system and changes the spin. The system then relaxes and other photons are emitted. This process is also known as optical pumping.
Getting the diamonds into position was no easy feat. The team had to spray an aerosolised nanodiamond dust solution into a 164 cubic centimetre box housing the lasers. Some of the nanodiamonds are attracted to the beam and will eventually become trapped though as graduate student Levi Neukirch explains: "it takes a couple of squirts and in a few minutes we have a trapped nanodiamond; other times I can be here for half an hour before any diamond gets caught. Once a diamond wanders into the trap we can hold it for hours."
Building upon this success, Vamivakas's team hopes to apply the technology towards nano sensory equipment that may help science explain some of physic's most fundamental conundrums. [University of Rochester via R&D Mag]