EUV ionization of pure He nanodroplets: Mass-correlated photoelectron imaging, Penning ionization and electron energy-loss spectra

D. Buchta; S. R. Krishnan; N. B. Brauer; M. Drabbels; P. O'Keeffe; M. Devetta; M. Di Fraia; C. Callegari; R. Richter; M. Coreno; K. C. Prince; F. Stienkemeier; R. Moshammer; M. Mudrich

doi:10.1063/1.4818531

arXiv · 1305.3726

EUV ionization of pure He nanodroplets: Mass-correlated photoelectron imaging, Penning ionization and electron energy-loss spectra

D. Buchta·S. R. Krishnan·N. B. Brauer·M. Drabbels·P. O'Keeffe·M. Devetta·M. Di Fraia·C. Callegari·R. Richter·M. Coreno·K. C. Prince·F. Stienkemeier·R. Moshammer·M. Mudrich

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Abstract

The ionization dynamics of pure He nanodroplets irradiated by EUV radiation is studied using Velocity-Map Imaging PhotoElectron-PhotoIon COincidence (VMI-PEPICO) spectroscopy. We present photoelectron energy spectra and angular distributions measured in coincidence with the most abundant ions He+, He2+, and He3+. Surprisingly, below the autoionization threshold of He droplets we find indications for multiple excitation and subsequent ionization of the droplets by a Penning-like process. At high photon energies we evidence inelastic collisions of photoelectrons with the surrounding He atoms in the droplets.

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D. Buchta, S. R. Krishnan, N. B. Brauer, M. Drabbels, P. O'Keeffe, M. Devetta, M. Di Fraia, C. Callegari, R. Richter, M. Coreno, K. C. Prince, F. Stienkemeier, R. Moshammer, M. Mudrich. 2013-05-16. EUV ionization of pure He nanodroplets: Mass-correlated photoelectron imaging, Penning ionization and electron energy-loss spectra. https://doi.org/10.1063/1.4818531

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