Strong Correlation And Alignment Near The Be 1S Photoionization Threshold

Photoionization in atomic beryllium has been studied in detail near the 1 s threshold. Multiple excitation to the 1 s ( 2 s 2 p 1 , 3 P ) states, i.e., conjugate shakeup, is found to be unusually strong, 40% of single excitation. The 3 P component rapidly loses strength with increasing photon energy, while the 1 P component persists. The 1 s 2 s 2 p states are highly aligned, as shown by the Auger-electron angular distribution. The A 2 value of -0.65 implies a d -wave contribution of 0.39. Our results indicate that resonances reported for the solid-state photoabsorption are of atomic origin