Electron–ion recombination rate coefficients of Be-like argon as a function of relative collision energy. The energy scale of the experimental spectrum (connected filled circles) was recalibrated by a factor of 1.06 to achieve agreement with the known 2s2p (1P1) nl series limit at 56.063 eV. Four ΔN = 0 DR series associated with ﹩2{s}^{2}\to 2s2p,{}^{1}{P}_{1},{}^{3}{P}_{\mathrm{0,1,2}}﹩ core excitations and parts of five ΔN = 0 TR series (﹩2{s}^{2}\to 2{p}^{2},{}^{1}{S}_{0},{}^{1}{D}_{2},{}^{3}{P}_{\mathrm{0,1,2}}﹩) can be observed. The corresponding resonance positions are indicated by short bars in different colors. The calculated DR and TR rate coefficients are shown by the gray area and the blue area, respectively. The sum of the theoretical DR and TR contribution is shown as a solid red line. This curve accounts for the experimental field-ionization cutoff (see the text). The orange line from 45 eV to 60 eV is the theoretical result including the full DR resonance strength up to nmax = 1000, called the field-ionization-free recombination rate coefficient.