title: Size-dependent high-order harmonic generation in rare-gas clusters.
abstract: High-order harmonic generation (HHG) is investigated in rare-gas clusters as a function of the cluster size using 0.8 and 1.3  μm femtosecond lasers. A characteristic, species-dependent knee structure in the single particle response is observed. A 1D recollision model qualitatively reproduces this behavior and associates it to the degree of delocalization of the initial wave function. Small clusters are observed to have a higher efficiency than monomers but rapidly lose this advantage as the size increases. The implications of these findings on the HHG mechanism in clusters are discussed.
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Hyunwook
authors.initials: H
authors.lastname: Park
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiong
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Schoun
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Junliang
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Agostini
authors.affiliation: Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Louis F
authors.initials: LF
authors.lastname: DiMauro