Black Gold Makes Bright Beams

Adapted from this Berkeley Lab Press Release

Gold-floored nanocavities are formed by grooves carved in gold-plated aluminum from a template produced by electron beam lithography. The grooves cause an order of magnitude electric field enhancement at the mouth of the nanocavity and a like enhancement of the magnetic field at its base. Incident laser light is normal to the surface.

For the high-rep-rate x-ray beams essential to next generation light sources, electron guns with photocathodes that can deliver tight electron bunches with high charge and high energy are essential. Early this week Physical Review Letters posted reports of two nanoscale arrays for photocathodes using resonating plasmons, based on principles developed by Howard Padmore of the Advanced Light Source (ALS). Led by the Molecular Foundry’s Alex Polyakov, one design is an array of gold-plated grooves that acts as a light trap and electron amplifier. The other is an array of nanoscale holes. Both open many new possibilities for the creation of ultrabright electron sources.

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