Physics Colloquium: Electrons Under Inspection

Physics Colloquium
Electrons Under Inspection: Probing Electron Dynamics Via High-Harmonic Generation

Dr. Kathryn Hamilton
Post-Doctoral Researcher
Drake University

Register here for Zoom Link
This seminar may be attended in person in A300 Gosnell Hall or online via Zoom.

Abstract:
Since their discovery in the late 1800’s, electrons have been a constant source of curiosity for scientists. Their properties and behaviour have been studied and harnessed to produce some of the greatest inventions of the past century, including electron microscopes and particle accelerators. However one fundamental question about their behaviour still remains: how do electrons move inside atoms and molecules?   Electron motion within atoms has proved difficult to study due to the incredibly short timescale it occurs on (the attosecond timescale, or 10-18 seconds). One method of capturing electron motion is to use very short laser pulses to take a series of snapshots of the system. This requires laser pulses shorter than the duration of the dynamics we want to observe (similar to using a short flash on a camera to obtain an image of a fast-moving object). The means to do this have only become possible in the past decade with the advent of new ultrashort (less than 100 as) lasers, which have become feasible due to a process called high‐harmonic generation (HHG).   Harmonic generation occurs when an atom is exposed to a short laser pulse. Electrons are removed from the atom by the laser field, accelerated, and then recombine with the parent atom emitting high-energy harmonic light. This light can then be manipulated to produce the attosecond pulses required to image electronic motion. Analysis of the spectra produced by harmonic generation can also give an insight on the attosecond‐scale dynamics of electrons. An accurate theoretical description of high harmonic generation would therefore be extremely beneficial for the advancement of attoscience.   To this end, a world‐leading computational method, known as RMT (R‐Matrix with Time dependence), has been developed at Queen's University Belfast to model accurately and efficiently the behaviour of electrons in many‐electron atoms. In this colloquium I will present recent results obtained using the RMT method, firstly to treat high-harmonic generation in two-color laser fields, and then on applications of the attosecond pulses generated during the HHG process to measure ionization delays. Finally, I will comment on planned future extensions of the RMT code, including an interface with the B-Spline atomic R-Matrix (BSR) code, and the operation of both codes via the Atomic, Molecular, and Optical Sciences (AMOS) Gateway.

Speaker Bio:
Kathryn Hamilton is Postdoctoral Research Scholar at Drake University in Des Moines, Iowa, where she works alongside Prof. Klaus Bartschat and the late Dr. Oleg Zatsarinny on applying R-Matrix methods to treat a variety of atomic and molecular physics problems. She obtained her PhD in 2019 under the supervision of Prof. Hugo van der Hart and Dr. Andrew Brown at Queen’s University Belfast with a thesis entitled “R-Matrix calculations for ultrafast two-colour spectroscopy of noble gas atoms”. Her current research focusses on observing and controlling multielectron dynamics in atoms exposed to external laser fields, and electron collisions with heavy atomic species. When she is not running code on supercomputers all over the world, she likes to play traditional Irish music on her violin, mandolin, or tenor banjo.

Intended Audience:
Beginners, undergraduates, graduates, experts. Those with interest in the topic.

To request an interpreter, please visit myaccess.rit.edu