The 4p-subshell photoabsorption spectrum of singly ionized molybdenum

The 4p-subshell spectrum of Mo⁺ has been recorded, for the first time, in the wavelength range 500–200 Å. The spectrum is dominated by a 4p → 4d 'giant resonance' on which extensive discrete structure is superposed. With only one exception the discrete lines can be ordered into six Rydberg series, 4p⁶4d⁵⁶S _5/2 → 4p⁵(4d⁵⁶S)(⁷P)ns,nd (J = 3/2, 5/2, 7/2), converging on three limits, the Mo III levels 4p⁵(4d⁵⁶S)⁷P _4,3,2. The observed spectrum is analysed by comparison with both Hartree plus exchange with relativistic corrections and relativistic time-dependent local density approximation calculations. The evolution of the discrete structure line shapes interacting with the giant resonance is found to be in qualitative agreement with the theory of Connerade and Lane (1987 J. Phys. B: At. Mol. Phys. 20 L181–6).