Collective enhancement of above threshold ionization by resonantly excited helium nanodroplets

Abstract

Clusters and nanodroplets hold the promise of enhancing high-order nonlinear optical effects due to their high local density. However, only moderate enhancement has been demonstrated to date. Here, we report the observation of energetic electrons generated by above-threshold ionization (ATI) of helium (He) nanodroplets which are resonantly excited by ultrashort extreme ultraviolet (XUV) free-electron laser pulses and subsequently ionized by near-infrared (NIR) or near-ultraviolet (UV) pulses. The electron emission due to high-order ATI is enhanced by several orders of magnitude compared to He atoms. The crucial dependence of the ATI intensities with the number of excitations in the droplets suggests a local collective enhancement effect.

References in corpus (2)

• Solving the m-mixing problem for the three-dimensional time-dependent Schrödinger equation by rotations: application to strong-field ionization of H2+
• Unravelling the Full Relaxation Dynamics of Superexcited Helium Nanodroplets

Cited by in corpus (3)

• Time-resolved Ultrafast Interatomic Coulombic Decay in Superexcited Sodium-doped Helium Nanodroplets
• Relaxation dynamics in excited helium nanodroplets probed with high resolution, time-resolved photoelectron spectroscopy
• Electron energy loss and angular asymmetry induced by elastic scattering in helium droplets