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arXiv · 2105.01918

Collective enhancement of above threshold ionization by resonantly excited helium nanodroplets

R. Michiels·M. Abu-samha·L. B. Madsen·M. Binz·U. Bangert·L. Bruder·R. Duim·A. Wituschek·A. C. LaForge·R. J. Squibb·R. Feifel·C. Callegari·M. Di Fraia·M. Danailov·M. Manfredda·O. Plekan·K. C. Prince·P. Rebernik·M. Zangrando·F. Stienkemeier·M. Mudrich
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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.

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R. Michiels, M. Abu-samha, L. B. Madsen, M. Binz, U. Bangert, L. Bruder, R. Duim, A. Wituschek, A. C. LaForge, R. J. Squibb, R. Feifel, C. Callegari, M. Di Fraia, M. Danailov, M. Manfredda, O. Plekan, K. C. Prince, P. Rebernik, M. Zangrando, F. Stienkemeier, M. Mudrich. 2021-05-05. Collective enhancement of above threshold ionization by resonantly excited helium nanodroplets. https://doi.org/10.1103/physrevlett.127.093201

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