CROSS-SECTIONS OF SYMMETRICAL CHARGE-TRANSFER BETWEEN GD-ASTERISK ANDGD-RANGE 30-1000 EV( IN THE ENERGY)

The charge-transfer cross section between a gadolinium atom and its po sitive ion has been measured with a crossed-beam apparatus that featur es primary ion production by photoionization with a tunable dye laser. The initial states of the Gd ions were controlled to be in the ground state by tuning the photon energy to be close to the ionization poten tial energy. The Gd ions in the ground states were collided with the G d atoms in the ground and some excited states. The cross sections as a function of impact energy (30-1000 eV) were successfully obtained. Th e cross section at 1000 eV was 3.3 x 10(-14) cm(2). The obtained cross sections were larger than those of other elements obtained experiment ally in the past.