Physical Chemistry Seminar (Douglas Natelson, Rice University)

Feb 25, 2016 at - | Lynch Lecture Hall Chemistry Complex

Inquires please contact Camille Pride at campride@sas.upenn.edu


Title: Plasmonic Junctions:  Vibrational tuning and heating at the molecular scale 




There is great interest in understanding quantum systems driven from equilibrium, though obtaining truly local information about dissipation and steady-state response is often difficult.  Over the last several years, we have developed nanoscale metal junctions that allow molecular-scale electronic transport measurements while also supporting unusual, highly localized plasmon modes ideal for surface-enhanced spectroscopies.  I will describe measurements that demonstrate electronically driven pumping of molecular vibrational modes at the single molecule level.  We also find that the application of voltage bias across the structure can systematically shift the vibrational energies of molecules within the junction.  Two recent sets of experiments (PNAS 111, 1282 (2014); Nano Lett. in press) show that these shifts result from both molecular charging (and screening) and the vibrational Stark effect.  Time permitting, I will discuss recent experiments that assess the contributions of both plasmons and direct absorption to the heating of these metal nanostructures.