INVESTIGATION OF HIGH-HARMONIC GENERATION FROM XENON ATOM CLUSTERS

We report on the generation df harmonic radiation (in the 70-90 nm ran ge) from clusters of similar to 10(3) Xe atoms formed in a gas jet. We find that the harmonic yield from the clusters exhibits an anomalous cubic scaling with backing pressure to the gas jet. This scaling is co nsistent with a cluster dipole moment resulting from collective oscill ations of electrons around the central ions of the cluster. Using a na nosecond ultraviolet prepulse to dissociate the clusters, we have also attempted to compare harmonic yields from clusters with those produce d from monatomic Xe, under otherwise identical conditions. Our results suggest that yields from clusters might exceed those from monomers by up to a factor of five.