X Rays from Superheavy Quasiatoms Transiently Formed during Heavy-Ion—Atom Collisions

X rays produced by 10- to 60-MeV I-ion bombardment on thick Au, Th, and U targets were analyzed with a high-resolution Si(Li) detector. The spectra can be understood in the framework of diabatic molecular orbitals. Radiative transitions in the quasimolecule formed during the collision are observed. These transitions between transient molecular orbitals may be interpreted as $M$ x rays of superheavy quasiatoms with nuclear charges of $Z=132,143,\mathrm{and} 145$.