Analytical Chemistry Seminar: Dan Hickstein
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Uncovering the structure and dynamics of a single nanoparticle using the world's shortest laser pulses
Dan Hickstein - Kapteyn-Murnane Group, JILA - University of Colorado
Modern femtosecond lasers can produce pulses of light that are shorter than the vibrational periods in molecules and generate electric fields stronger than the Coulomb field that binds electrons in atoms. These lasers are ideally suited to studying ultrafast processes in nanomaterials, such as electron transfer in photovoltaic nanostructures. However, all previous laser-nanoparticle experiments have been conducted on nanoparticles suspended in solvent, embedded in a bulk material, or attached to a surface, meaning that powerful gas-phase spectroscopy techniques cannot be used. In 2011 we embarked on a collaboration with the Jimenez group to construct a photoelectron–photoion spectrometer capable of examining isolated nanoparticles in the 'gas phase.' To our surprise, the completed spectrometer was capable of recording the complete photoion distribution resulting from the interaction of a single nanoparticle with the femtosecond laser pulse. This breakthrough technique has allowed for the examination of localized light fields in nanostructures, the discovery of shock waves in nanoscale plasmas, and the observation of the evanescent wavefunction in quantum dots. In this talk I describe how we combined the tools of physical chemistry, laser physics, and atmospheric science to construct this new instrument, describe the discoveries to-date, and discuss our plans for future experiments, which include pushing the time-resolution towards the attosecond frontier.