Nam wins DURIP award to image corrugated 2D materials using nano-infrared technology

Assistant Professor SungWoo Nam was selected for a highly competitive Defense University Research Instrumentation Program (DURIP) award from the Air Force Office of Scientific Research (AFOSR).

DURIP awards enhance research capabilities at universities conducting cutting-edge research through the procurement of state-of-the-art equipment. Nam plans to acquire a dual mode nanoscale infrared (nano-IR) spectroscopy/imaging platform, which combines atomic force microscopy (AFM)-IR spectroscopy and AFM-based scattering SNOM (s-SNOM) imaging technology to enable nanoscale infrared microscopy and chemical imaging of deformed two-dimensional materials like graphene.

Through his proposed project, “Nanoscale Infrared Spectroscopy and Imaging: Enabling Nanoscale Plasmonic/Optical Interrogation of Corrugated Two-dimensional Materials,” Nam hopes to experimentally validate his recent theoretical findings in this area. He said that, to his knowledge, such complementary capability has yet to be demonstrated with corrugated 2D materials due to diffraction-limited resolution of conventional aperture-limited SNOM or confocal microscopy techniques.

Dual mode nano-IR platform is unique in that it combines the complementary techniques of AFM-IR and AFM-based s-SNOM. AFM-IR directly detects light absorbed by the sample using an AFM probe tip to sense thermal expansion. This thermal expansion depends primarily on the sample’s absorption coefficient, and is largely independent of the other optical properties of the tip and sample—making the AFM-IR technique preferred for measurements where an accurate absorption spectrum is desired.

Additionally, AFM-based s-SNOM detects light scattered by nanometer-scale regions directly under the AFM probe tip. The scattered field depends on the complex optical constants of both the tip and sample and contains rich information about nano-optical phenomena. By accessing both the non-radiative (AFM-IR) and radiative (s-SNOM) information on plasmonics structures, unique and complementary plasmonic properties can be investigated.

“The success of the research proposed in this grant will yield a deeper understanding of the nature of plasmons in corrugated graphene by directly mapping and visualizing plasmonic resonance using dual mode nano-IR. I also hope I will be able to apply this new nano-IR capability to other 2D materials to explore the excitation and modulation of their optical properties,” Nam said.

Nam’s grant, through the Department of Defense, was one of just 175 awarded to university researchers at 91 institutions, totaling $53 million. The awards are administered through a merit competition jointly conducted by the Army Research Office, Office of Naval Research, and Air Force Office of Scientific Research.