  Complex coordinate scaling (CCS) is used to calculate resonance eigenvalues
and eigenstates for a system consisting of an inverted Gaussian potential and a
monochromatic driving field. Floquet eigenvalues and Husimi distributions of
resonance eigenfunctions are calculated using two different versions of CCS.
The number of resonance states in this system increases as the strength of the
driving field is increased, indicating that this system might have increased
stability against ionization when the field strength is very high. We find that
the newly created resonance states are scarred on unstable periodic orbits of
the classical motion. The behavior of these periodic orbits as the field
strength is increased may explain why there are more resonance states at high
field strengths than at low field strengths. Close examination of an avoided
crossing between resonance states shows that this type of avoided crossing does
not delocalize the resonance states, although it may lead to interesting
effects at certain field strengths.
