J. Bernard et al., DOUBLE RYDBERG STATES IN STABILIZED TRIPLE CAPTURE IN BARE IONS (Z=6-10) ON RARE-GAS TARGET COLLISIONS, Physica scripta. T, T73, 1997, pp. 190-192
We report converging evidence from two different coincidence experimen
ts of the formation of triply excited states C3+(2, n, n') and Ne7+(3,
n, n') with two n, n' (n and n' much greater than 3) Rydberg electron
s. They are formed by triple electron capture in collision of C6+ and
Ne10+ bare ions with Ar at few keV. This detailed study was triggered
by measurements of surprisingly large cross sections of stabilized tri
ple electron capture (STC) for which a full radiative decay leaves the
three electrons bound to the projectile. Both the energy gains and th
e visible photon spectra support the interpretation in term of a large
population of triply excited double Rydberg states among which some s
tates decay without autoionization. For both systems, possible populat
ion mechanisms are discussed in term of purely atomic mechanisms occur
ring in the post collisional evolution of the quasi symmetrical triply
excited states initially populated by the collision.