SSO Seminar
Wednesday, May 2, 2012 - 16:00 to 17:00
Weniger 304
Event Speaker: 
Michael Paul (OSU Physics)
Local Contact: 
Yun-Shik Lee

Talk #1

Title: Terahertz Transmission Ellipsometry of Vertically-Aligned Multi-Walled Carbon Nanotubes

Abstract: We demonstrate time-resolved terahertz transmission ellipsometry of vertically-aligned multi-walled carbon nanotubes. The angle-resolved transmission measurements reveal anisotropic characteristics of the terahertz electrodynamics in multi-walled carbon nanotubes. The anisotropy is, however, unexpectedly weak: the ratio of the tube-axis conductivity to the transverse conductivity is merely 2.3, which is constant over the broad spectral range of 0.4-1.6 THz. The relatively weak anisotropy and the strong transverse electrical conduction indicate that THz fields readily induce electron transport between adjacent shells within multi-walled carbon nanotubes.

Talk #2

Title: Terahertz Imaging of Inhomogeneous Electrodynamics in Single-Layer Graphene Embedded in Dielectrics

Abstract: We investigate electron transport properties in large-area, single-layer graphenes embedded in dielectric media, using free-space THz imaging and time-domain spectroscopy. Two different types of graphene layer, sandwitched by a thin PMMA layer and a Si substrate, exhibit distinctive spatial inhomogeneity of sheet conductivity. The non-contacting, non-destructive THz probe reveals that the PMMA layer induces a small, yet noticeable reduction in conductivity.