Atomic Vibration Characteristics in Semiconductor Nanowires: Rodolfo Lopez
Major: Physics, minor in
Chemistry
University: California State
University-Stanislaus
Year: Sophomore
REU Program:
Physics
Advisor:
Assistant Professor Yi Gu
Rodolfo Lopez researches white wine as a sophomore at California State University-Stanislaus. This summer, however, he is an REU student at Washington State University’s studying the temperature dependence of atomic vibrations in zinc oxide semiconductor nanowires with Yi Gu, assistant professor in WSU’s department of Physics and Astronomy.
Semiconductor nanowires are one-dimensional nanoscale materials with the diameter of 1~100nm and the length of several micrometers, and they exhibit many novel optical, electrical, thermal, and mechanical properties. Atomic vibrations in these materials contain critical information on the electronic as well as thermal properties.
In Gu’s lab, Lopez uses a technique called “Raman scattering spectroscopy” to measure the frequencies of atomic vibrations in zinc oxide nanowires as a function of temperature. Raman spectroscopy relies on the scattering of monochromatic (single wavelength) light, usually from a laser. The laser light interacts with atomic vibrations in the system, which results in the energy of the laser photons being shifted up or down. The shift in energy provides information about the different modes of vibration in the system.
Since vibrational information is specific for the chemical bonds in molecules, Raman spectroscopy provides a fingerprint by which a molecule can be identified. The studies on atomic vibrations, such as Lopez’s summer research, may shed light on the origin of many unique properties that have been observed in nanowires.
“Obtaining Raman data from single nanowires
is a quite challenging task,” says Gu. “But
Rodolfo has been very successful in this regard. He is
an intelligent and hard-working student.”
Back at CSU-Stanislaus, Lopez works
with Scott Russell in the Chemistry department to
identify heat-unstable proteins in white wines. These
proteins leave an unmarketable, cloudy suspension in
the wines. Lopez and his research partner remove the
haze from the wine and do certain procedures to digest
and break down the proteins into peptides.
“The goal of this research,” states Lopez, “is to be able to develop a process that would efficiently remove these proteins without affecting other important characteristics of wine such as taste, aroma, and color, which people expect from a wine.”
Lopez says his interest in chemistry was a “mistake” at first. “I accidentally wrote down that I wanted to study chemistry instead of physics when I was a freshman,” he explains. “After taking a few chemistry classes, I knew that physics was still my main academic passion but if I can get a minor in chemistry I will definitely do that.”
“I would recommend undergraduate research, just for the learning experience,” says Lopez. He has enjoyed WSU and being in the physics REU has been a memorable experience for him that he wouldn’t mind repeating.
Lopez plans to stay in California for graduate school and then pursue physics research for a career.
"I really wasn't expecting to have this much fun with my research," says Lopez of his physics REU experience at WSU.