Photoionisation of atomic arsenic

The photoionisation spectrum of atomic arsenic prepared by successive abstraction reactions involving H atoms and AsH 3 , has been obtained from its ionisation threshold at around 1266.6 to 745 AA. A number of s-like and d-like autoionisation resonance series have been identified converging to 3 P 1 and 3 P 2 of As + . At least one of the d-like series is broad and asymmetric. In addition, at higher energies a deep window resonance series is seen, involving inner s-shell excitation to . . . ( 5 S)np 4 P states. The quantum defect for this series is in good agreement with recent Hartree-Slater calculations.