arXiv subjects

B. Gruener

Publications and source records attributed to B. Gruener.

3 recordsLinked to original sources

arXiv2016

Efficiency of Dopant-Induced Ignition of Helium Nanoplasmas

Helium nanodroplets irradiated by intense near-infrared laser pulses ignite and form highly ionized nanoplasmas even at laser intensities where helium is not directly ionized by the optical field, provided the droplets contain a few dopant atoms. We present a combined theoretical and experimental study of the He nanoplasma ignition dynamics for various dopant species. We find that the efficiency of dopants to ignite a nanoplasma in helium droplets strongly varies and mostly depends on (i) the pick-up process, (ii) the number of free electrons each dopant donates upon ionization, and remarkably, (iii) by the hitherto unexplored effect of the dopant location in or on the droplet.

physics.atm-clus↗

arXiv2012

Formation and relaxation of RbHe exciplexes on He nanodroplets studied by femtosecond pump and picosecond probe spectroscopy

Vibrationally resolved photoionization spectra of RbHe exciplexes forming on He nanodroplets are recorded using femtosecond pump-probe spectroscopy with amplitude-shaped probe pulses. The time-evolution of the spectra reveals an exciplex formation time ~10ps followed by vibrational relaxation extending up to >1ns. This points to an indirect, time-delayed desorption process of RbHe off the He surface.

physics.atm-clus↗

arXiv2011

Imaging spectroscopy of rubidium atoms attached to helium nanodroplets

Highly excited states of rubidium (Rb) atoms attached to helium (He) nanodroplets are studied by two-photon ionization spectroscopy in combination with electron and ion imaging. Photoion spectra and angular distributions are in good agreement with a pseudodiatomic model for the RbHe_N complex. Repulsive interactions in the excited states entail fast dissociation followed by ionization of free Rb atoms as well as of RbHe and RbHe_2 exciplexes. Nonresonant excitation generates Rb atoms in low-lying electronic levels by statistical evaporation-like desorption.

physics.atm-clus↗