Graduate Student - Ph.D.

Chemistry

University of Illinois at Urbana-Champaign (Urbana, IL)

Martin Gruebele

Single Molecule Absorption Spectra Detected by Scanning Tunneling Microscopy

The scanning tunneling microscope (STM) is a powerful tool for the study of surfaces and adsorbates due to its high spatial resolution. The addition of optical excitation to the STM introduces a means for examining single-molecules with high spatial and spectral resolution simultaneously. We utilize rear-illumination and frequency-modulation of a laser excitation source to overcome the thermal problems association with optically-assisted STM. We directly detect absorption in molecules by monitoring changes in their electronic structure. Carbon nanotubes have generated significant interest due to their unique physical properties and may find use in a number of nanotechnologies. We use our single-molecule absorption monitoring technique to probe the optical absorption spectrum of the first electronic transition of semi-conducting single-walled carbon nanotubes on silicon surfaces. Discrepancies exist between the calculated optical spectra and experimental spectra measured with other techniques. We aim to use our spatially-resolved direct-detection method to resolve these inconsistencies.

2004-2006 Teach For America - Corps Member

2006 National Science Foundation Graduate Research Fellowship - Honorable Mention

2006-2007 University of Illinois Teaching Award