05/02/19 - 9:45 AM to 11:00 AM
Department Seminar: Professor Vartkess "Ara" Apkarian
Spectromicroscopy with Atomically Confined Light
Plasmonic nanojunctions can be used to effectively confine light on the Å scale, surpassing the diffraction limit by four orders of magnitude, and opening the atomistic limit in optical microscopy. Seeing an atom, a single chemical bond, imaging the vibrational normal modes inside one molecule, seeing intramolecular currents, and seeing sound are among the recent observations made in our laboratory under the rubric of tip-enhanced Raman spectro-microscopy (TERS). I will use these examples to expand on the unusual properties and multiple facets of atomistically confined plasmons and their applications. As light, the momentum uncertainty associated with spatial confinement gives visible photons the wavelength of x-rays, which allows the simultaneous energy and momentum matching conditions required to see dispersive acoustic phonons, to see sound. As fields, the dramatic enhancement through confinement allows detection of the feeble Raman effect from individual molecules, giving access to the electro-mechanical machinery and opto-electronic circuitry of individual molecules for sensing and device applications. As cavity photons, superpositions of only two Fock states can be prepared and maintained. And in the quantum tunneling limit required for atomistic resolution, fields and photocurrents associated with the time harmonic charge density oscillations provides the more natural description of confined light. There is rich photophysics at plasmonic nanojunctions.
V. Ara Apkarian is a professor of chemical physics at the University of California, Irvine, and director of the National Science Foundation Center for Chemical Innovation on Chemistry at the Space-Time Limit (2007-present). He holds bachelor's and doctorate degrees in chemistry from the University of Southern California and Northwestern, respectively. Following a post-doctoral fellowship in Cornell, he joined the chemistry faculty at UCI in 1983. He has served as department chair (2004-2007) and as the founding co-director of the Chemical and Materials Physics (ChaMP) program at UCI (1997-2000). He is a Fellow of the American Physical Society and American Association for the Advancement of Science, a Foreign Member of the National Academy of Sciences of Armenia, and has been recognized with awards in teaching, service and research, including the Humboldt Prize and, more recently, through the American Chemical Society Award in Experimental Physical Chemistry.
Professor Apkarian's scientific contributions are in photophysics and molecular and quantum dynamics in condensed matter. His work, which combines experiment and theory on a wide range of topics, has appeared in more than 150 peer-reviewed publications. His current research combines ultrafast methods with plasmonics, scan-probe and electron microscopy to interrogate single molecules in real-time and with atomic spatial resolution.