For robust fluorescence, do it yourself in the microwave
David L. Shenkenberg
Quantum dots fluoresce brightly and for a long time compared with conventional dyes such as fluorescein, but making them hasn’t been easy. Typically, they are assembled commercially in multiple steps and are baked at 300 °C in an oven inside which the gas levels are controlled. Who has time?
Researchers from the National Institute of Standards and Technology in Gaithersburg, Md., decided to pop the quantum dots into the microwave. Although not the first to make them in a microwave, they created the little buggers in just two steps with no special gases and at half the temperatures of commercial processes and made them water-soluble without the problematic “ligand exchange” process.
They created uniformly sized quantum dots that still fluoresce brightly in a range of colors and that remain stable in water after more than six months (see picture).
- An electromagnetic wave lying within the region of the frequency spectrum that is between about 1000 MHz (1 GHz) and 100,000 MHz (100 GHz). This is equivalent to the wavelength spectrum that is between one millimeter and one meter, and is also referred to as the infrared and short wave spectrum.
- quantum dots
- Also known as QDs. Nanocrystals of semiconductor materials that fluoresce when excited by external light sources, primarily in narrow visible and near-infrared regions; they are commonly used as alternatives to organic dyes.
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