title: Charge transfer and penning ionization of dopants in or on helium nanodroplets exposed to EUV radiation.
abstract: Helium nanodroplets are widely used as a cold, weakly interacting matrix for spectroscopy of embedded species. In this work, we excite or ionize doped He droplets using synchrotron radiation and study the effect onto the dopant atoms depending on their location inside the droplets (rare gases) or outside at the droplet surface (alkali metals). Using photoelectron-photoion coincidence imaging spectroscopy at variable photon energies (20-25 eV), we compare the rates of charge-transfer to Penning ionization of the dopants in the two cases. The surprising finding is that alkali metals, in contrast to the rare gases, are efficiently Penning ionized upon excitation of the (n = 2)-bands of the host droplets. This indicates rapid migration of the excitation to the droplet surface, followed by relaxation, and eventually energy transfer to the alkali dopants.
authors: Physikalisches Institut, Universität Freiburg, 79104 Freiburg, Germany.
authors: Dominic
authors: D
authors: Buchta
authors: Siva R
authors: SR
authors: Krishnan
authors: Nils B
authors: NB
authors: Brauer
authors: Marcel
authors: M
authors: Drabbels
authors: Patrick
authors: P
authors: O'Keeffe
authors: Michele
authors: M
authors: Devetta
authors: Michele
authors: M
authors: Di Fraia
authors: Carlo
authors: C
authors: Callegari
authors: Robert
authors: R
authors: Richter
authors: Marcello
authors: M
authors: Coreno
authors: Kevin C
authors: KC
authors: Prince
authors: Frank
authors: F
authors: Stienkemeier
authors: Robert
authors: R
authors: Moshammer
authors: Marcel
authors: M
authors: Mudrich