The Curious White Batch of Silver Nanoparticles

In my time spent working with silver nanoparticles I found them to be undependable in every aspect except that they are dependable as a constant supply of new questions to answer. At three weeks in, I am dedicating time to reflect upon my original motivations for this project. My journey with these particles began last summer when a curious batch of white silver nanoparticles were mistakenly synthesized instead of the expected murky green solution. The particles were immediately deemed as inviable and poured into a waste container. However, my curiosity lead me to run tests on these white particles anyways. The resultant spectrum exhibited the highest intensity for any batch of nanoparticles I had ever seen. This surprising discovery lead to a plethora of questions like: Why are they more intense? Is the white batch more concentrated than the green batch? What happened during the synthesis that caused this batch to be so different from what was expected?

Furthermore, the most important question –  does a high intensity spectrum mean that these particles are better at amplifying the signal of organic art pigments? – has driven my research for the past year. I made many batches of silver nanoparticles and collected as much data as possible to better understand how these particles behave. I know now that intensity is just one of many aspects that contribute to the enhancement factor of the particles. Enhancement factor is normally calculated in the literature by comparing the intensity of spectra of an analyte taken via normal Raman spectroscopy, or spectroscopy without the use of nanoparticles as enhancing agents, with spectra taken using surface-enhanced Raman scattering spectroscopy (SERS). I cannot directly calculate enhancement factor in this way because the dyes and pigments that I want to identify fluoresce during normal Raman spectroscopy which prevents identification. My current pursuit is to find a way to measure the ability of a batch of silver nanoparticles to amplify the signal of organic art pigment and dyes through means that do not require data from normal Raman spectroscopy.



  1. pglynch says:

    It sounds like you have a lot of questions to answer! Hopefully reflecting on the reasons for starting your project will be helpful, since you have been working on answering these questions for a while. Have you found that going back to your original motivations has helped you to focus on one specific aspect of the nanoparticle synthesis? I am really interested to find out how you can make the syntheses more consistent and find a way to measure enhancement factor more reliably. My advisor likes to say that good research produces more questions than answers, so it seems like your on the right track!

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