Penning spectroscopy of acetylene molecules dissolved in superfluid He nanodroplets reveals the loosely held molecular aggregate collapsing into a covalently bound oligomer ion upon indirect ionization effected by the photoexcited He* in the host.

In this paper, a 3-dimensional photoelectron/ion momentum spectrometer (reaction microscope) combined with a table-top attosecond beamline based on a high-repetition rate (49 kHz) laser source is presented. The beamline is designed to achieve a temporal stability below 50 attoseconds. Results from measurements on systems like molecular hydrogen and argon dimers demonstrate the capabilities of this setup in observing the attosecond dynamics in 3D while covering the full solid angle for ionization processes having low cross-sections.

The acetylene-vinylidene system serves as a benchmark for investigations of ultrafast dynamical processes where the coupling of the electronic and nuclear degrees of freedom provides a fertile playground to explore...

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Synopsis Complete measurements of photoionization include both time-resolved and angle-resolved mapping of the atomic and molecular dynamics. The setup described in this work is suited to be used for attosecond pump-probe experiments as well as providing insights into the angular dependencies of photoionization.