University of Illinois
Excited state structure and dynamics of nanomaterials via STM-imaged absorption spectroscopy
Unlike small molecules, which can be synthesized with atomic precision, very large molecules from DNA to carbon nanotubes have unavoidable defects The interesting properties of such materials usually involve energy or charge migration in the excited state, and such dynamics is affected, and sometimes even controlled, by defects. For this reason, the interpretation of spectra is more difficult, and it can be nice to have not just time- and energy-information about the system, but also about its wavefunction, at least in the form of excited state electron density of the system. I will discuss how single molecule absorption scanning tunneling microscopy (SMA-STM) can provide such information, allowing the visualization of excited states by sub-nanometer resolution, tomography of excited state orbital structure for individual particles, and even femtosecond time evolution of the electron density of a nanoparticle to be visualized, to make a direct connection with nanomaterials structure.