EXPLOSIONS OF ATOM CLUSTERS YIELD HIGH ENERGIES . Femtosecond lasers can be used to convert chemical energy into kinetic energy with great pyrotechnic effect. For example, they can blow up molecules, imparting a kinetic energy of 100 eV to individual outgoing ions. Aiming fsec pulses at a solid can produce ions with keV energies. Now scientists at Imperial College (London) have observed much higher energy ions (up to 1 MeV) flying away from the miniature fireball caused by shooting ultrashort (150 fsec), high-intensity (2 x 10¹⁶W/cm²) laser pulses at clusters of xenon atoms. It is not yet understood why clusters explode so much more violently than molecules. The researchers look on their explosions as a novel and modest way of achieving high-temperature plasmas in a gas of clusters. They point to the possibility of tabletop fusion experiments. (T. Ditmire et al., Nature, 6 March 1997.)