Oscillator Strength Measurements of Even-Parity Autoionizing Resonances by Combined Synchrotron-Radiation-Laser Excitation

We have obtained oscillator strengths for transitions between a laser-excited initial state and autoionizing final states. In the case of sodium, a laser was used to populate the $3p$ initial state, and synchrotron radiation was used to excite the autoionizing resonances. These transitions are of the type 2p⁶3p²P→2p⁵(²P)3s3p(1,3P)2,4S,2,4P,2,4D; they decay to 2p⁶¹S+e. The sum of the oscillator strengths for all the observed transitions between the 2p⁶3p initial-state and the 2p⁵3s3p final-state configurations was found to be equal to 0.22(4).