• Prof Misha Ivanov
  • Prof Jon Marangos

High harmonic spectroscopy of electron-hole dynamics

During the past decades, laser laboratories have developed the capability to produce remarkably short and intense light pulses, often containing a single oscillation of the carrier wave. This new capability comes with unprecedented control over the light oscillations. Shining these pulses on physical systems, we push them into new regimes, and we can use their response to follow in real time not only the motion of the nuclei inside a molecule, but also the (much faster) motion of electrons within it, at their natural timescales.

On the theory side, these capabilities allow us to build more detailed and meaningful models of these phenomena, including completely new ones such as high-harmonic generation, in which an electron is removed from a molecule by a short laser pulse, and later on re-collides with the parent ion to produce an even shorter pulse of light. These elaborate models can then be put to the experimental test to inform and guide finer and more interesting models as well as using these effects as tools to probe new dynamics, such as using high harmonic generation to probe the interactions of the ionized electron with the positively charged hole it leaves behind.

My research currently focuses on a detailed description of the ionization process through the optical tunnelling effect, and the possibility that the leaving electron induces transitions in the ion while it is still inside the tunnelling barrier. This breaks with the usual paradigm of tunnelling phenomena that freezes all other degrees of freedom during the tunnelling step. I am developing schemes to experimentally test the detailed predictions of our model, including, for example, the high harmonics produced during re-collision. These techniques can hopefully then be generalized to more complex systems such as dielectrics.

Masters Thesis