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Physics students take on a summer challenge
Taneka Lewis, a senior at Wheeling Jesuit University, worked in the laboratory of Prof. Volkmar Dierolf through the physics department’s summer REU program.
Each year about 20 students from around the country, most of them from other universities, participate in the competitive Research Experience for Undergraduates (REU) program in the department of physics.

The 10-week program began in 1983 and has been funded for nearly 25 years by the National Science Foundation. It gives qualified students the opportunity to work on a research project with a faculty member and graduate students while receiving a stipend and living on campus.

Two REU students this summer were Taneka Lewis of Wheeling Jesuit University in West Virginia and Kathryn “KC” Reddy of Fordham University in New York.

Lewis heard about Lehigh’s REU program from a professor at her home university. She spent the summer working with Volkmar Dierolf, chair of the physics department, and his research group in optics and photonics.

Shedding light on vibrating atoms

Lewis used the techniques of Raman spectroscopy and confocal microscopy to study the effect of light on lithium niobate, a transparent compound that can be used to guide light waves and is used for light modulators in the optical networks that power the Internet. By determining how atoms in the compound vibrate, she could infer how light induces electrical  fields in the compound.

Any lab experience is not just about the science, but also the people with whom one works. In Lewis’ case, she found that Dierolf and her lab mates, the graduate students, were very supportive.

“Dr. Dierolf was definitely the ideal person to work with this summer,” she said. “And the office was its own little family. Each person helped out.”

An assist from an Einstein equation

Reddy, who participated in the REU program in 2012, came back to Lehigh to continue working with her adviser, Daniel Ou-Yang, professor of physics.

Last summer, Reddy used optical tweezers combined with electrophoresis, which are a means of manipulating the movement of particles trapped in a liquid suspension. The optical tweezers involve the use of a highly focused laser to manipulate an individual particle while electrophoresis involves applying an electric field to move the electrically charged particle. By studying how the particles move in the suspension under different force field, Reddy could quantify the effects due to the different forces on the particles.

After her summer experience, Reddy returned to Fordham but remained in contact with her group at Lehigh. With encouragement from Ou-Yang, she created a poster of the work she did at Lehigh in 2012 and gave an oral presentation at the American Physical Society’s March Meeting in Baltimore and at research symposiums at Fordham and Syracuse University.

This summer Reddy explored something entirely different from what she did last summer. By subjecting particles in liquid suspensions to centrifugation she worked to understand sedimentation equilibrium of the particles in suspension. Using an equation developed by Einstein in one of his three famous papers published in 1905, and used by Jean B. Perrin when he determined Avogadro’s number and won the 1926 Nobel Prize in physics, Reddy was able to determine the thermodynamic equation of the state of electrically charged colloidal particles in water.

When asked to compare her experience at Lehigh with her experience at her undergraduate institution Reddy said that at Lehigh she was given more leeway to figure things out and try out her own ideas.

But help was there when she needed it.

“The post-docs and graduate students really care about you personally,” she said.

In addition to conducting research, REU students also take part in a number of social activities including river rafting, a trip to nearby Dorney Park, intramural softball and an outing to a local Iron Pigs baseball game. These enable students to interact with each other as well as their professors.

“It was really a great opportunity to break the ice,” said Lewis.

When this year’s REU program ended in late July, Lewis and Reddy returned to their home universities to complete their undergraduate degrees.

Lewis’s experience in the lab at Lehigh confirmed her decision to pursue a research career in engineering specializing in robotics. Reddy, on the other hand, plans to continue as a research physicist. Her experiences with Ou-Yang taught her that she “definitely wants to do experiments,” possibly in biophysics.

Some solid science and a bit of fun round out a complete summer in the Lehigh physics department’s REU program.