I am synthesizing graphene quantum dots using glucose and DI water and pyrolyzing the solution in a microwave. To prove synthesis occured, I am using DLS to measure the size of the quantum dots. I started off with an 11.1% wt. solution and increased to 22.2% wt. but only saw an increase in counts from 9 kcps to around 28 kcps. How can I increase this count without raising the concentration even higher?
I make the solution using 4.44 g of glucose, dissolve it in 20 mL of DI in a 20 mL glass vial, and heat it in a 700W microwave. The solution does decrease in volume during heating to
Hi Anya,
Do you mind sharing what instrument you are using?
The detected intensity of scattering in a DLS measurement depends on incident laser intensity, particle concentration, particle RI, particle size, scattering angle and detection volume.
Obviously some one of these are fixed for you. Laser intensity is the easiest to adjust but more light also means more noise, so most commercial instruments will optimise the incident laser intensity.
Based on my literature research, the solution should turn a yellow color indicating the presence of QDs. All my samples have turned yellow. Furthermore, I did UV-measurements, on some of the first samples and found that my peaks correlate with those in my literature searches. So I am pretty confident they are there
I would try shining a laser pointer through your sample at a low concentration (
Alexander Malm I am using a Malvern-Zetasizer DLS instrument. I adjust the Attenuator to 11, as well as the refractive index to that of carbon. My solvent is water and I use disposable cuvettes.
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