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Growing up, Therese Karitanyi ’07 (Kigali, Rwanda) had little exposure to snowflakes. But since coming to Lafayette she has not only seen her fair share of the cold crystals, she has conducted experiments with crystals of a different nature.
Working this summer with Andrew Dougherty, associate professor of physics, Karitanyi grew microscopic crystals from amonium chloride to predict their growth patterns.
In addition to being interesting to look at, the way crystals grow reveals characteristics of less delicate materials, such as metals, says Karitanyi.
“With some alloys and metals, in order for us to know what some of their properties are, we need to look at the microstructure,” says Karitanyi, who is pursuing a B.S. degree in chemical engineering and an A.B. while majoring in international studies. “But since the metals are opaque, it’s hard to look at the alloys themselves–like copper and aluminum–so we put aluminum chloride under a microscope and look at its crystals.”
Karitanyi and Dougherty worked together through Lafayette’s distinctive EXCEL Scholars program, which allows students to conduct research with faculty while earning a stipend. The program has helped to make Lafayette a national leader in undergraduate research. Many of the more than 160 students who participate each year share their work through articles in academic journals and/or conference presentations.
Dougherty says looking at characteristics of crystals to determine the properties of metals is a convenient system.
“The patterns we see here are very similar to what you see in metals, but they’re at a temperature that’s convenient and they’re transparent so we can see them,” he says. “We looked at determining the particular sizes, what controls size, how fast they grow, what controls the speed–those are the things required [in order to know] how many you would need to grow to make an alloy.”
Dougherty said the crystals seem to start growing fairly regularly, but become more erratic as time goes on.
“We [investigated] what sets the barometer between the orderliness and disorderliness of these patterns and thought about what happens if we give it a nice kick — how does it respond,” he explains.
That means Karitanyi had to make very minute, precise changes in the temperature of the crystal during very specific stages in its growth.
For instance, depending on the temperature, a crystal can grow or melt very quickly. If the experiment called for melting the crystal down to one single branch, she had to melt it very slowly and stop the melt at exactly the right moment, she says.
In addition to learning precision in her measurement and patience in conducting experiments, her work with Dougherty taught her to think about the world around her differently, she adds.
“It’s really interesting to me. At first it was just the whole idea of the project; when I came in, I didn’t even know that amonium chloride had the same structure as some of those metals,” Karitanyi says. “The crystals are so little, but everything comes from there and affects so many things on a bigger scale.
“Sometimes I just sat and started thinking about things–everything has a microstructure and that’s what defines it.”
Dougherty sentiments mirror his student’s.
“I always come back to watching them grow. They’re very beautiful; they’re not perfectly symmetrical, but they come close,” he says. “They live in the delicate balance between order and disorder that makes so many things in life interesting.”
Karitanyi says her work has given her an understanding that all science, including the meshing of millions of tiny crystals to form a bigger metal alloy, is intertwined and works together as part of a bigger picture.
“In class you get it and they tell you, ‘This is how it is,’ and you just accept it,” she adds. “Here you actually are tying to figure out how it works and why it works like that.”
Dougherty believes this research will enhance Karitanyi’s college experience.
“[Students] get a different exposure here than they would in a classroom setting. And the opportunity to really direct, to help determine, what comes next is unique to a research project.”
Karitanyi is a peer adviser for the International Students Association, event coordinator for Lafayette African and Caribbean Students Association, and a member of Students for Social Justice and the Society of Women Engineers. She also sings in the concert choir.
As a national leader in undergraduate research, Lafayette sends one of the largest contingents to the National Conference on Undergraduate Research each year. Forty-two students were accepted to present their work at the last annual conference in April.