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Collisions of 16 0 ions on targets of 94 2 197A 208Pb, and 232 111. . d • .d r, u, are 1nvest1gate at mc1 ent energies of 140 and 315 MeV, and compared to published data on peripheral collisions at 33.6 GeV. At 140 MeV, the isotope-production cross sections resemble the ground-state Q-value systematics characteristic of a partially-equilibrated, di-nuclear system formed in deeply-inelastic scattering. The yields are independent of shell and pairing effects in the target and residual nuclei. These Q-value systematics fail at 315 MeV, where the relative element yields are similar to those at 33.6 GeV. A theory of projectile fragmentation accounts for. .

Excitation functions have been measured for di6'erent fragments produced in the ' Y{' F,x)y reactions between 135 and 143.25 MeV incident energy in 250 keV steps. Cross section fluctuations correlated in atomic number and detection angle arg observed with a coherence width of 200 -500 keV. Lifetimes have been deduced and are of the order of a complete nuclear rotation. The data can be explained in terms of quasimolecular configurations and/or an orbiting situation in a dinuclear system.