FIELD-IONIZING LENS SYSTEM FOR THE DETECTION OF HIGH RYDBERG STATES IN MULTICHARGED IONS OF KEV ENERGIES

A new detector for state analysis of multicharged ions, excited in hig h Rydberg states, at kinetic energies of the order of keV is described . It is composed of a field-ionizing lens system (FILS), associated wi th two electrostatic spectrometers; the first one, in front of the FIL S, selects the q-times charged excited ions of interest, and the secon d one, behind the FILS, analyzes the (q+1)-times charged ions resultin g from field ionization according to their kinetic energy. The princip le of the FILS is to generate a linearly increasing electric field, co linear with the excited ion beam, that the excited multicharged ions e xperience until they are field ionized. This detector has been success fully used to detect fur the first time he distributions of very high Rydberg n states in the domain rt = 67-100 produced in Kr7+ (n) ions by electron capture into Kr8+ from laser-excited Rb(n(i)p) atoms. (C ) 1997 American Institute of Physics.