18 TABLE IX: Comparison of theoretical and experimental transition energies. Units are MHz for He and Li + and cm − 1 for other ions. Results by Drake are from 2005 for He [31], from 1994 for Li + [37], and from 1988 for other ions [5]. Z This work Drake Experiment Reference 2 $^{3}$P$_{0}$ –2 $^{3}$S$_{1}$ transition: 2 276 764 094.7(3.0) 276 764 099(17) 276 764 094.678 8(21) [1] 3 546 560 686(32) 546 560 627 546 560 683.07(42) [37] 4 26 864.6114(47) 26 864.64(3) 26 864.612 0(4) [38] 5 35 393.628(14) 35 393.70(8) 35 393.627(13) [39] 8 60 978.85(14) 60 979.6(5) 60 978.44(52) [40] 10 78 263.98(39) 78 265.9(1.2) 78 265.0(1.2) [40] 2 $^{3}$P$_{1}$ –2 $^{3}$S$_{1}$ transition: 2 276 734 477.7(3.0) 276 734 476(17) 276 764 477.724 2(20) [1] 3 546 404 980(31) 546 404 885 546 404 978.80(51) [37] 4 26 853.0534(47) 26 852.04(3) 26 853.053 4(3) [38] 5 35 377.429(14) 35 377.40(8) 35 377.424(13) [39] 8 61 037.65(14) 61 037.7(5) 61 037.62(93) [40] 2 $^{3}$P$_{2}$ –2 $^{3}$S$_{1}$ transition: 2 276 732 186.1(2.9) 276 732 183(17) 276 732 186.593 (15) [1] 3 546 467 655(31) 546 467 553 546 467 657.21(44) [37] 4 26 867.9450(47) 26 867.92(3) 26 867.948 4(3) [38] 5 35 430.088(14) 35 430.02(8) 35 430.084(9) [39] 8 61 589.21(14) 61 589.0(5) 61 589.70(53) [40] 10 80 122.3(4) 80 121.6(1.2) 80 121.53(64) [41] 2 $^{1}$P$_{1}$ –2 $^{1}$S$_{0}$ transition: 4 16 276.775(4) 16 276.77(3) 16 276.774(9) [42] 2 $^{3}$P$_{1}$ –2 $^{1}$S$_{0}$ transition: 7 986.36(7) 986.6(3) 986.3180(7) [43]