Public Lecture | Clocking Electrons: an Attosecond Stopwatch by Siqi Li

Electrons in a molecule zip around the atom in times measured in billionths of a billionth of a second, or attoseconds. To learn the basic mechanisms of chemical reactions – how catalysts work, how batteries operate – we need to follow electrons over these very short times, and for that, we need a stopwatch that ticks in attoseconds. In this lecture, I will explain how we use SLAC's X-ray laser, the Linac Coherent Light Source (LCLS), to measure times in attoseconds. Part of the challenge is to verify that the stopwatch is accurate. This work provides tools to watch electrons move on their natural time scales.

About the Speaker:

Siqi Li is a staff scientist at SLAC in the group responsible for operating our X-ray free-electron laser, LCLS. After receiving her bachelor's degree at the University of Chicago, she came to SLAC and Stanford for graduate study, leading to her PhD in 2019. Her thesis on the production and measurement of attosecond X-ray beams won the 2020 award for the Outstanding Doctoral Thesis in Beam Physics given by the American Physical Society. After graduating, Li joined the SLAC staff, where she continues to improve the technology that enables ultrafast science.

[keybutnolock]

Great stuff. Very well explained - Thanks for sharing.

[Tight_Conduct]

I really appreciate this upload! After so many youtubers talking about it, it's nice to hear from someone who knows so intimately what's actually going on.

[kwgm]

Siqi Li, that was a very good presentation. Thank you for making the ideas easy to understand. It is great to see new physics again being birthed at SLAC.

In the mid-1970s I remember being told, as a young engineering student, that the facility once helped probe the proton, but is now obsolete. In the 1980's I would drive 280 South under the long building that holds your experiment on my daily commute, wondering if anythig was happening there. By then I learned the colliders were two miles long, and that 25 years earlier in a physics experiment, 'something' was scattering high energy electrons fired at an atomic nucleus. The data from the early SLAC experiments, and from others like it, would later bring Gell-Mann to call that something a quark, after a line in James Joyce's famous nonsense poem.

[nyckhusan]

You already can measure position of electron clouds in the atoms of molecules in 1000 attoseconds frames. What about position of electron cloud in the single hydrogen atom? If period of rotation of electron cloud is about 150 attoseconds and you create series of photon pulses 150 attoseconds each and direct them on atom can you assign resulted position of electron cloud as " 1 " when electron is hit and "0 " when 75 attoseconds elapsed?

[davidwilkie]

Brilliant stuff and requires a rather long elaboration...

Or in Principle, Euler's e-Pi-i 1-0-infinity instantaneous quantization cause-effect format for the infinitesimal coordination-identification positioning system of universal quantization calculation holography dimensionality is moderately brief. The picture-plane containment of Singularity-point i-reflection superposition containment-condensation modulation cause-effect says "All is Vibration" relative-timing ratio-rates Perspective Principle as demonstrated.

[ferozex.]

can it overcome heisenberg uncertainty?