The God Quasiparticle: The Plasmon and Infrared Spectroscopy of Proteins

When: Thursday, February 06, 2014 at 4:00 pm
Where: DA 114
Speaker: Professor Shyam Erramilli
Organization: Boston University
Sponsor: Physics Colloquium

The Plasmon is the first Quasiparticle to be discovered. Collective macroscopic quantum excitations of electrons in metals were described nearly a hundred years ago, but it is only recently that we have begun to appreciate some of their truly extraordinary properties. One example is a remarkable phenomenon called “Extraordinary Optical Transmission”, first discovered only in 1997, in which a nanoscale pinhole in a metal sheet  transmits light more than a hundred times more efficiently than predicted by conventional theory.  An intense effort is now going on to control and enhance the properties of plasmons for vibrational infrared spectroscopy of proteins and other biomolecules.

Combining simulations of the Maxwell equations with electron beam lithography, new metamaterial structures can be created.  We have shown experimentally that plasmons can be used to enhance the absorption of infrared light in proteins by several hundred thousand. Recently, we have also shown that plasmonic metamaterials can actually also suppress absorption. This trick may be useful for canceling strong infrared absorption in water. Our observations confirm the predictions of coupled-mode theory which offers an elegant framework to design and create purpose-built materials for infrared spectroscopy in biomolecules.  The field of  “Plasmonic Metamaterials”  is arguably the fastest growing field in Physics today. Given the extent of interactions and scope of applications,  the Plasmon may indeed be called “the God Quasiparticle.”

Host: Assistant Professor Meni Wanunu