Volume 228, 2021

Manipulating twisted electrons in strong-field ionization


We investigate the discrete orbital angular momentum (OAM) of photoelectrons freed in strong-field ionization. We use these ‘twisted’ electrons to provide an alternative interpretation on existing experimental work of vortex interferences caused by strong field ionization mediated by two counter-rotating circularly polarized pulses separated by a delay. Using the strong field approximation, we derive an interference condition for the vortices. In computations for a neon target we find very good agreement of the vortex condition with photoelectron momentum distributions computed with the strong field approximation, as well as with the time-dependent methods Qprop and R-Matrix. For each of these approaches we examine the OAM of the photoelectrons, finding a small number of vortex states localized in separate energy regions. We demonstrate that the vortices arise from the interference of pairs of twisted electron states. The OAM of each twisted electron state can be directly related to the number of arms of the spiral in that region. We gain further understanding by recreating the vortices with pairs of twisted electrons and use this to determine a semiclassical relation for the OAM. A discussion is included on measuring the OAM in strong field ionization directly or by employing specific laser pulse schemes as well as utilizing the OAM in time-resolved imaging of photo-induced dynamics.

Graphical abstract: Manipulating twisted electrons in strong-field ionization

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Article information

Article type
14 Sep 2020
22 Oct 2020
First published
22 Oct 2020
This article is Open Access
Creative Commons BY license

Faraday Discuss., 2021,228, 394-412

Manipulating twisted electrons in strong-field ionization

A. S. Maxwell, G. S. J. Armstrong, M. F. Ciappina, E. Pisanty, Y. Kang, A. C. Brown, M. Lewenstein and C. Figueira de Morisson Faria, Faraday Discuss., 2021, 228, 394 DOI: 10.1039/D0FD00105H

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