Autoionizing states of He: projectile velocity dependent lifetime

S. OTRANTO; C. R. GARIBOTTI; F. D. COLAVECCHIA; G. GASANEO

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 2001 vol. 63 p. 227131 - 227136

1050-2947

In this work, we study the dependence of the lifetime ( tao ) of an autoionizing state with the velocity ( v P ) ofan ionic projectile of charge Z. We use a C2 model to represent the final state of the autoionized electron in thecontinuum of two centers. Explicit calculations for the helium autoionizing states 2s 2 ( 1 S), 2p 2 ( 1 D), and2s2p( 1 P) are analyzed. We evaluate the decay law for the metastable initial state and find that tao increases asthe projectile becomes faster and converges to the photoionization lifetime for high impact energies. A scalinglaw for tao is obtained in terms of the Sommerfeld parameter (Z/ v P ). Finally, we evaluate the transitionprobability for the autoionized electron and show that the mean half-width of the focusing peak decreases as v Pincreases.