Image of the Week 20/02/17

By Thomas Farrell on February 20, 2017

Today’s Image of the Week comes from a paper published as part of JPhysB‘s Special issue: emerging leaders. This special issue features invited work from the best early-career researchers working within the scope of JPhysB. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. In this case Professor Joshua Williams was selected by the Editorial Board of JPhysB as an Emerging Leader.

In a paper entitled Born in weak fields: below-threshold photoelectron dynamics, J B Williams et al study the dynamics of ultra-low kinetic energy photoelectrons both theoretically and experimentally. Weak electric extraction fields are used in experiments to detect photoelectrons. These weak fields effect the dynamics of these electrons. In this work, the authors study these effects by creating photoelectrons with synchrotron radiation. The figure below shows an example of the agreement they find between their experiments and theoretical predictions.

The energy (photon energy offset by to the field-free threshold) versus the effective electron momentum in the z-direction with the color scale indicating the counts for a 40 V cm–1 extraction field. Top row shows theoretical calculations and the bottom row shows experimental data. The overlaid vertical black curve shows the mean value of the momentum distribution. On the bottom row, the horizontal black line is the fit error of the mean which result from the Gaussian fit. In column (A) the polarization is orientated parallel to the extraction field. In column (B) the polarization is orientated perpendicular to the extraction field.

The energy (photon energy offset by to the field-free threshold) versus the effective electron momentum. Top shows theoretical calculations, the bottom shows experimental data. The overlaid vertical black curve shows the mean value of the momentum distribution. On the bottom row, the horizontal black line is the fit error of the mean which result from the Gaussian fit. In column (A) the polarization is orientated parallel to the extraction field. In column (B) the polarization is orientated perpendicular to the extraction field, from J B Williams et al 2017 J. Phys. B: At. Mol. Opt. Phys. 50 034002 © IOP Publishing, All Rights Reserved.

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This work is licensed under a Creative Commons Attribution 3.0 Unported License. Image taken and front image adapted from J B Williams et al 2017 J. Phys. B: At. Mol. Opt. Phys. 50 034002 © IOP Publishing, All Rights Reserved.