Line narrowing and reversal in profile symmetry caused by intrachannel mixing of (5dnd)J=0 autoionizing Ba Rydberg series

Using high resolution laser spectroscopy the authors have investigated linewidths and line profiles of (5d32/nd32/)J=0 autoionizing Rydberg states of barium for principle quantum numbers n=14 up to n=99. Configuration interaction with (5d52/n'd52/)J=0 perturbing states (n'=11-14) causes resonant variations in linewidths, inhibition of autoionization (n=26, 60, 61), and a reversal in profile symmetry for Rydberg states (n=66-99) located within the broad contour of the (5d52/14d52/)J=0 perturbing resonance. Linewidths and line profiles were successfully analysed employing a three-channel quantum-defect model.