New laser system at Miami beams red, green and purple to the delight of molecules
Students in physics lab manipulate molecules' love of color and speed
Current spectroscopy group members: front, Briana Vamosi; left to right, Jacob McFarland, Phill Arndt, Patrick Boyle and Burcin Bayram. A $150,000 National Science Foundation grant supports this research. (Photo by Jeff Sabo)
Written by Carole Johnson, university news and communications, and Trevor Jordan, intern
New ultrafast laser technology now at Miami University will help researchers and students better understand energy transfer processes in collisions between atoms and molecules — applicable in the fields of biology, medicine, engineering and quantum physics.
The newly installed lasers allow researchers to greatly increase the resolution of the interaction time between atoms and molecules and to manipulate how they interact and react with polarized light. The support from a $150,000 National Science Foundation grant made it possible for Miami to acquire the laser system. The grant was awarded (July 2013) to Burcin Bayram, associate professor of physics at Miami.
Miami graduate and undergraduate students are training with the various models of lasers in Bayram’s lab. Students learn the techniques of fast and ultrafast time-resolved laser spectroscopy – the study of the reaction of atoms and molecules to light. A variety of lasers with different light colors are used in the projects.
“We can fine-tune the color of the laser light from purple to red and probe reaction of the molecules because molecules can absorb, emit and even scatter the light at a particular color,” Bayram said.
Phill Arndt shows undergraduate students Briana Vamosi and Jacob McFarland about the operation of a cw ring dye laser cavity (Coherent 699) pumped by Coherent Verdi at 7.5 W, 100 MHz. Bayram received three lasers recently; picosecond laser system, high power Coherent Verdi 100MHz green laser and cw Coherent ring dye laser. (Photo by Jeff Sabo)
Creating disorder in molecules
Phillip Arndt, a physics graduate student, explains that the group will first manipulate the internal properties of the states of molecules with an ultrashort laser beam to create disorder in the angular momentum of molecules. This causes the molecules to begin rotating and oscillating at a specific rate.
A small amount of pressure of background gas is then presented to agitate the system, causing the oscillations of the angular momentum to lessen quickly. A second ultrashort probe laser will arrive after a time delay to measure the alteration.
By varying the delay time between the two lasers as short as a few picoseconds (equivalent to a few trillionths of a second), time evolution of the molecular properties can be mapped out. Altogether, these studies can provide an exceptional spectroscopic precision and understanding of the various energy transfer processes, explained Bayram.
“This method is like using a stroboscope to map out the different energies as a function of time,” said Arndt. “This is neat, and it’s not something that can be bogged down with theory.”
Implications in various science fields
The grant directly supports Bayram’s “Polarization Quantum Beat Spectroscopy in Diatomic Molecules” program that will focus on the technology and its implications in various fields of science. Visit the Bayram Research webpage.
Bayram has provided one-on-one research mentorship to 32 undergraduates and 12 graduate students since she joined Miami in 2002. She teaches advanced laboratory and molecular spectroscopy, calculus-based physics at the introductory level for science and engineering majors and physics at the introductory level for non-science majors.