Observation ofZ=70QuasiatomicKX Rays from 30- and 60-MeVBr35+Br35Collisions

A $K$-x-ray band up to the united-atom limit for $Z=70\mathrm{}$ has been observed in 30- and 60- MeV Br + Br collisions. This band can be assigned unambiguously to transitions between molecular orbitals. With a KBr target, yields at the two energies are (for $E_x>~22$ keV) 2 × ${10}^{-8\mathrm{}}$ and ${10}^{-7\mathrm{}}$ photons/projectile, respectively, or ${10}^{-4\mathrm{}}$ photons/beam $K$ vacancy, nearly independent of beam energy. Much reduced yields are found for Ti, Fe, and Zr targets.