Chakraborty, researchers publish findings of time-span of electrons’ choral dance in sub-nanometer particles

An international research group involving a Northwest Missouri State University physics professor has published its latest research of fullerenes in a prestigious academic journal.

Dr. Himadri Chakraborty, a member of the Northwest faculty since 2006, co-authored the research paper, “Correlation-driven attosecond photoemission delay in the plasmonic excitation of C60 fullerene,” which appears in the Feb. 14 edition of Science Advances, a high-impact multidisciplinary journal published by the American Association for the Advancement of Science.

“In nanometer size matters, a plasmon is a highly collective, highly correlated electron motion – a party, which results in extreme energy confinement,” Chakraborty said. “Nanoplasmonics therefore has applications in photovoltaics energy-harvesting, energy transport, developing molecular switches, supplying electrons for chemical catalysis and as molecular-size electron sources. The control on these processes will significantly enhance if we know the lifetime – existence time – of the plasmon state as a function of energy.”

Dr. Himadri Chakraborty

The ground-breaking research emerged from theory and simulations largely developed at Northwest and led by Chakraborty and Dr. Maia Magrakvelidze, a former post-doctoral research associate at the University. The experiments were conducted jointly by groups at labs in Hamburg and Munich in Germany; Milan, Italy; and at Stanford University.

The research group employed attosecond laser-spectroscopy to investigate the plasmon dynamics of the most abundant and stable carbon molecule, called Buckminsterfullerene, C60. Using attosecond photoemission spectroscopy, researchers precisely computed and measured the delay required for an electron to escape a molecule during plasmonic excitation.

An attosecond is a billionth of a billionth of a second. Fullerenes are soccer-ball-shaped, cage-like molecules – within a billionth of meter, or nanometer, in size – that are composed of carbon atoms. They display giant plasmonic resonances at extreme ultraviolet energies, which can trigger photoemission.

“The delay is the time of the electron’s participation in the plasmonic dance before leaving the party,” Chakraborty said.

The electron, the research group found, accumulates a photoemission delay ranging from a minimum of 50 attoseconds to about 300 attoseconds, depending on its kinetic energy. The findings show the increasing importance of electronic correlations in the collective-electron plasmon response as the size of the system decreases to sub-nanometer scales.

A computational nanophysicist, Chakraborty is the recipient of multiple National Science Foundation grants for his research of carbon fullerene molecules and related derived materials. His prolific work has been appeared in high-impact periodicals, including Physical Review journals published by American Physical Society.

Most recently Chakraborty co-authored an article published Feb. 20 in The Journal of Physical Chemistry A, “Ultrafast Nonadiabatic Electron Relaxation Dynamics in Photoexcited C60 Molecules,” with Dr. Esam Ali, a former post-doctoral research associate; Dr. Ruma De, a current post-doctoral research associate; and Matthew Wholey, who graduated from Northwest last spring with a bachelor’s degree in physics.

In addition to employing a number of post-doctoral researchers through grant funding, Chakraborty consistently involves undergraduate students in his research. Those undergraduate students have gone on to pursue master’s and doctoral degrees in physics, chemistry, material science and engineering. His students also have been nominated to The Council on Undergraduate Research as distinguished graduates.

“The computational aspects enrich nanoscience and computational physics teaching courses directly,” Chakraborty said. “The research impact will hopefully benefit in winning future grant awards, which will broaden student research involvements. All these will hopefully positively impact enrollments and retention.”

To learn more about Chakraborty’s research, visit es3b.86899805.com/naturalsciences/directory/sites/Chakraborty/.