title: Probing the 2D to 3D structural transition in gold cluster anions using argon tagging.
abstract: Different physisorption properties by 2D and 3D isomers of Au_{n};{-} clusters are observed and used to probe the 2D to 3D structural transition. Strong Ar clustering occurs on planar Au_{n};{-} and the planar faces of the pyramidal Au20-. An abrupt change of Ar clustering at Au12- confirms the 2D to 3D structural transition at this size, where both isomers coexist. The minor 2D isomer can be titrated out by Ar to produce a clean 3D-Au12- beam and beams of Au_{12}Ar_{m};{-} with enhanced 2D isomers. Using the Ar titration and tagging, isomer-specific photoelectron spectra for the 2D and 3D Au12- are obtained.
authors.affiliation: Department of Physics, Washington State University, Richland, Washington 99354, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang