What do colloids do?

Hello, everyone! I don’t know if you remember but this summer I’m working in Professor Kristin Wustholz’s lab using Surface-Enhanced Raman Scattering (SERS) to identify dyes in paintings created by Charles Willson Peale. When I came in this summer I had an official list of things I wanted to get done and learn. They were: [Read more…]

Reproducibility of known Auto Paints

Step two for my research over the summer is reproducibility of known auto paints from a collision center. These are not actual auto paints samples from the manufacturer but paints used by the collision center to match the manufactured paint. Over the past semester, we had identified a specific Raman spectrum using surface-enhanced Raman spectroscopy for a particular paint. My goal was to simply reproduce this spectrum. Reproducing something is often much harder then it sounds unfortunately. After much trial and error, I was able to reproduce the spectrum on multiple samples on different days. Success! I was also able to reproduce the spectrum of the other paints provided by the collision center. Through the reproduced spectra, I was also able to prove that the chromophore or pigment used by the specific collision center was the same for all the paints. Double-success! Step three is to obtain an identifiable spectrum from auto paints actually from the manufacturer.

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Have you ever watched colloids dry?

At the beginning of the summer I developed a series of steps that I need to complete in order to have a successful summer researching auto paints. The first step was stabilizing the colloidal silver nanoparticles that my lab uses; we call them colloids for simplicity. Colloids are a suspension of silver nanoparticles in a sodium citrate and water solution. Stable colloids can be applied to auto paint samples, amongst other substances, for surface-enhanced Raman spectroscopy analysis. The trick is getting them to remain stabilized. Over the past semester, our colloids were only stable for a max of two days. The lifespan of colloids should be upwards of two weeks. After reviewing the procedure that we had been using all semester, we found some flaws. We discovered that our sodium citrate was expired by three years and that we were not boiling the silver nitrate enough before adding the sodium citrate. We corrected these two details and now we have colloids that last for three weeks! With stabilized colloids, I am able to move on to step two, reproducibility of auto paint standards.

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Applying Surface-Enhanced Raman Scattering to the Conservation of Art Works

Hello, everyone! My name is Marisa Choffel, and I am a rising senior here at W&M. I’m majoring in Chemistry and minoring in Computer Science. I’ve been working in Dr. Kristin Wustholz’s lab for the last two semesters, and I look forward to working in the lab this summer.

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Application of Surface-Enhanced Raman Spectroscopy to Forensic Auto Paint Analysis

Hello everyone! Have you ever been in a situation where your car was involved in a hit and run accident? Usually when this happens a paint sample is left behind by the car that hit you. This paint sample can be used in forensic analysis to identify the car of the offender. My research over the summer will be in applying a new analytical method in order to solve this common crime amongst other crimes involving paint evidence.

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