Dopant induced ignition of helium nanodroplets in intense few-cycle laser pulses

TL;DR

This paper demonstrates that doping helium nanodroplets with a few atoms enables ultrafast laser-induced ignition, leading to complete ionization and disintegration, even when pristine droplets are transparent to the laser.

Contribution

It reveals that dopant atoms can induce rapid ignition in helium nanodroplets with few-cycle laser pulses, a process not observed in undoped droplets.

Findings

Less than 10 dopant atoms ignite the droplet.

Complete ionization occurs within approximately 9 fs.

Pristine helium droplets remain transparent under the same conditions.

Abstract

We demonstrate ultrafast resonant energy absorption of rare-gas doped He nanodroplets from intense few-cycle (~10 fs) laser pulses. We find that less than 10 dopant atoms "ignite" the droplet to generate a non-spherical electronic nanoplasma resulting ultimately in complete ionization and disintegration of all atoms, although the pristine He droplet is transparent for the laser intensities applied. Our calculations at those intensities reveal that the minimal pulse length required for ignition is about 9 fs.