Lasers can be used to induce the emission of electrons from ions through a process called photodetachment. Particularly interesting to those working in strong field atomic physics is photodetachment in negative ions by femtosecond laser pulses. In a recent paper in JPhysB, Shear and Law consider theoretically photodetachment of negative silicon ions by femtosecond infrared lasers.

2D photoelectron momentum spectrum for Si- in a linearly polarized field, from S F C Shearer and S M K Law J. Phys. B: At. Mol. Opt. Phys 48 055402
The Image of the Week shows a plot of the momenta of the electrons emitted by photodetachment in the Si– ion in two dimensions. Distinctive is the concentric ring structure that can be seen in the spectrum, which is caused by the quantized frequency components of the laser pulse.
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Front Image and article image: 2D photoelectron momentum spectrum for Si- in a linearly polarized field, adapted from S F C Shearer and S M K Law 2015 J. Phys. B: At. Mol. Opt. Phys. 48 055402
Categories: Journal of Physics B: Atomic, Molecular and Optical Physics, JPhys+