title: Metastable Aluminum Atoms Floating on the Surface of Helium Nanodroplets.
abstract: Metal atoms have proved to be sensitive probes of the properties of superfluid helium nanodroplets. To date, all experiments on the doping of helium droplets have concentrated on the attachment of metal atoms in their ground electronic states. Here we report the first examples of metal atoms in excited states becoming attached to helium nanodroplets. The atoms in question are aluminum, and they have been generated by laser ablation in a metastable quartet state, which attaches to and remains on the surface of helium droplets. Evidence for a surface location comes from electronic spectra, which consist of very narrow absorption profiles that show very small spectral shifts. Supporting ab initio calculations show there to be an energy incentive for a metastable Al atom to remain on the surface of a helium droplet rather than move to the interior. The results suggest that helium droplets may provide a method for the capture and transport of metastable excited atomic and molecular species.
authors.affiliation: Department of Physical and Theoretical Chemistry, School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Jay
authors.initials: J
authors.lastname: Jeffs
authors.affiliation: Department of Physical and Theoretical Chemistry, School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Besley
authors.affiliation: Department of Physical and Theoretical Chemistry, School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Stace
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarma
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Cunningham
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: Adrian
authors.initials: A
authors.lastname: Boatwright
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: Shengfu
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Ellis