Correlation satellites in the photoelectron spectrum of argon

Many-body perturbation theory has been used to calculate photoionization cross sections with excitation of neutral argon from the single-ionization threshold at 15.76 to 100.00 eV. Resonance structure due to both single-electron excitations (3s{→}np) and double-electron excitations (3s²3p⁶{→}3s²3p⁴mn) has been included. Calculated cross sections leaving the ion in 3s²3p⁵, 3s3p⁶, 3s²3p⁴{(}¹$D)md${(}²$S), and 3${s}²$3${p}⁴$4p${(}²$P) levels are compared with experiment and previous calculations. Calculated cross sections for 3${s}²$3${p}⁶→3s3{p}⁶εp and 3{s}²3p→3{s}²$3${p}⁴$4p{ε}d/{ε}s excitations were used to determine the satellite intensities, which are compared with photoelectron measurements and other calculations. Results are also presented for the total cross section and the angular-asymmetry parameter for 3p electrons.