Generation of cooler, ultrafast electron packets via mid-IR driven nanostructures

A detailed comparison of ultrafast electron emission from structured, silicon nano-tips driven by 800 nm and 2.1 μm pulses was performed. In the low energy portion of the spectrum, a saturation of the direct electron energy bandwidth to ≈1.6 eV for 800 nm and ≈ 1 eV for 2.1 μm was observed.