Photoionization in atomic beryllium has been studied in detail near the $1s$ threshold. Multiple excitation to the $1s\left(2s2p{}_{}{}^{1,3}{}_{}{}^{}P\right)$ 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 $1s2s2p$ 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.

• Received 13 August 1987

DOI:https://doi.org/10.1103/PhysRevLett.59.2736