Researcher finds golden opportunity to advance explosive detection
Shaun Galvan makes an observational analysis of a solution containing synthesized silver nanoparticles as part of his research with the U.S. Department of Homeland Security HS-STEM Summer Internship Program. Photo courtesy of Jackie Mcbride, Lawrence Livermore National Laboratory.
When Shaun Galvan, a chemistry major at the University of California, Irvine, learned that his interest in chemistry could contribute to U.S. national security, he quickly narrowed his list of 2011 summer internship opportunities to one—the U.S. Department of Homeland Security HS-STEM Summer Internship Program.
Galvan was introduced to Raman spectroscopy during a previous research experience at the University of Wollongong in Australia. This technique involves firing a monochromatic laser beam at an unknown material and capturing the Raman signal. The increase or decrease in energy detected in the Raman signal, as compared to the laser, allows researchers to identify the molecular makeup of the material. For materials, like explosive substances, that produce weak signals, scientists use Surface Enhanced Raman Spectroscopy, or SERS, which is a variation of this technique that employs a roughened metal surface, typically gold or silver, to enhance the signals.
Law enforcement officials need to quickly identify and detect explosive substances from even minute traces of evidence. However, conventional analytic tools, such as trained dogs or the ion mobility spectrometry used in airports, offer only limited detection and identification of many common explosives. SERS is a promising approach, but advances are needed to strengthen the signals. Galvan is working with The Advanced Materials Synthesis Group at Lawrence Livermore National Laboratory to create specialized gold and silver particles with extremely irregular surfaces to concentrate trace amounts of explosives for more effective SERS analysis.
Galvan is engineering a variety of gold and silver particles to find the design that offers the greatest Raman signal enhancement for identification of an explosive substance. By concentrating the molecules of the explosive, the team will increase the probability that SERS will quickly detect and correctly identify it. The ultimate goal of the project is to one day design a system for remote sensing of both explosives and chemical agents that will keep human operators at a safe distance.
“Nanoparticle design and shape control are some of my biggest challenges involved in this project,” explained Galvan. “I’m attempting to design uniform ‘popcorn-shaped’ particles which were discovered recently and have only been synthesized by one other research group—so far they have created the greatest enhancement.”
Galvan credits his internship with providing opportunities to explore new areas of chemical research well beyond the typical undergraduate experience. He is working with the latest in published research on nanoparticle design, and he has learned to use several chemical devices, including Raman laser systems and scanning electron microscopy.
As he pursues his goal to become a chemistry professor, Galvan embraces the atypical and varied life of a research scientist. “There are days where I am on the Internet searching for articles that report cutting-edge research that may be applicable to my project objectives. There are days when you handle some of the most advanced and expensive machinery you will ever come in contact with, and there are days when you will have to present your findings to your mentor or to an audience. It’s typical of research to not be typical.”
The DHS HS-STEM Summer Internship Program provides a 10-week summer research experience for undergraduate students majoring in homeland security related science, technology, engineering and mathematics disciplines. The goal of this program is to prepare a diverse, highly talented, educated, and skilled pool of scientists and engineers to address homeland security STEM issues. The program is administered by ORISE.