Room 6C/6E Catching Electrons in the Act:: Attosecond Dynamics in Metals and Semiconductors

Friday, October 12, 2012: 8:00 PM
6C/6E (WSCC)
Desiré Whitmore, PhD , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
Andrey Gandman, PhD , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
James Prell, PhD , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
Lauren Borja, B.S. , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
Daniel Neumark, PhD , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
Stephen Leone, PhD , Chemistry/Physics, University of California, Berkeley, Berkeley, CA
Here, we extend attosecond (10-18 second) spectroscopic and photoelectron-based techniques to investigate the motion and damping of electronic phenomena in the solid state, which occurs on timescales shorter than a few femtoseconds.   Isolated extreme ultraviolet (XUV) light pulses of ~100 attoseconds are generated using high harmonic generation for the study of these dynamics.

Irradiation of metal nanostructures with resonant near infrared or visible light can induce collective oscillations of free electrons, known as localized surface plasmons (LSPs).   We have investigated the few-femtosecond decay of LSPs in metal nanoparticles using a combination of electron time-of-flight, velocity map imaging, and XUV spectroscopic techniques.  We demonstrate that electrons ejected with ~100 attosecond XUV pulses from nanoparticles supporting LSPs driven by a few-cycle carrier pulse at 400 nm can be used to map out the electric field decay at the surface of the nanoparticle as the delay time between the visible and XUV pulses is varied. 

Semiconductors have several uses in modern day technology including cellular phones and solar cells.  Solar cells, in particular, have a long way to go in order to advance their efficiency.  Excitonic formation inside of semiconducting materials is the primary catalyst for the conversion of light into electricity.  By generating an electron-hole pair with an XUV pulse the formation of the exciton, as well as the recombination of electron and hole are studied on an attosecond time scale.  These results will lead to the production of more efficient solar cell material.