Luminescent Nanoparticles as Nanothermometers

by Ben Maloy

Mentor: Igor Sokolov, Mechanical Engineering; Funding source: Nathan Gantcher Student Summer Scholars Fund

Thermodynamics at the nanoscale is ill-defined, and our research this summer was aimed at finding more details about energy fluctuations and thus temperature at said scale. To do so, luminescent nanoparticles at a fixed temperature were filmed with an Andor-Solis microscopic camera. The ratio between 2 spectral ranges (ranges of light wavelength that the camera detects), can be used to find the temperature of the system, because the brightness of the particles is affected by temperature.

            However, imaging at this small of a scale (particles are around 50nm) is also tricky, because even a small amount of instrumental noise can complicate the brightness measurement process. The main task of this lab was to collect data by measuring the brightness of blocks of pixels that correspond on both sides. Measuring the brightness of the pixels requires subtraction of the background noise, which is discussed in the poster. Shifting data points from one side to the other was also involved, mainly because initial data points had to be found by looking at the images and deciding where image points corresponded. Then a best fit curve would approximate where a point on the left would be found on the right.

            A similar technique was used when finding the background using what I call the ‘best fit method’ in the poster. Both rely on visually confirming some aspect of the image data. Once this data is acquired, the task falls to computer programs. We wrote a lot of code this summer for fitting the data to make the aforementioned approximation functions (for shifting and background), and then actually getting the brightness with the boxes also relied on a program that would read the movie in as a sequence of pictures and collect data frame by frame. Let me know if you have any questions about the code involved!

            Many thanks to Dr. Sokolov and Anne Moore for their guidance.