The spectrum of Mg4+ was observed between 95 and 400 Å. New wavelengths result in revised-energy level values and some resolved term structure. Parametric calculations with configuration interaction were made for the 2s2p5, 2s22p33s, and 2s22p33d configurations. These support rejection of some levels and some new identifications.
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Uncertainty on the measured wavelengths is estimated to be ±0.005 Å.
Intensities are visual estimates, (af indicates that a close line affected the measurement.)
The line at 97.440 Å was previously1 classified as 2p43P2–2s2p4(4P)3p3D3, the other transitions of the multiplet being blended with Mg viii (97.606 and 97.686 Å). This identification is rejected because the resulting level at 1 026 270 cm−1 would be much higher than the predicted position for 2s2p4(4P)3p levels.
This line was observed but not classified by Söderqvist.1 Kelly and Palumbo6 reported the lines 99.610 and 99.788 Å as 2p43P2,1–2p3(4S)5s3S1 transitions. This would locate the 2p3(4S)5s3S1 level at 1 003 900 cm−1, but this value is not consistent with the expected quantum-defect variation. Therefore, Söderqvist’s identification1 of 2p3(4S)5s3S1 at 1 002 130 was preferred. The level at 1 003 900, if real, may possibly be 2s2p4(4P)3p3D.
For these lines, we give the wavelengths of Johannesson et al.2 which we confirmed within ±0.003 Å.
The identification of this line was established by Fawcett et al.3
TABLE II
Energy levels of Mg4+.
Configuration and parent
Term
J
Level (cm−1)
2s22p4
3P
2
0.0
1
1 783.1
0
2 521.8
1D
2
35 926
1S
0
77 279
2s2p5
3P°
2
283 212.3
1
284 828.3
0
285 712.0
1P°
1
397 482
2p6
1S
0
662 970
2s22p3(4S)3s
3S°
1
684 540
(2D)3s
3D°
3
727 740
2
727 760
1
727 780
1D°
2
735 550
(2P)3s
3p°
0
756 550
1
756 570
2
756 640
1P°
1
764 630
2s22p3(4S)3d
3D°
1
821 970
2
821 990
3
822 070
(2D)3d
3D°
3
871 220
2
871 360
1
871 390
1P°
1
873 460
3P°
2
876 790
1
877 280
0
877 460
1D°
2
877 610
3S°
1
879 510
1F°
3
882 790
(2P)3d
3P°
0
898 760
1
898 960
2
899 370
1D°
2
901 470
3D°
3
902 150
2
902 510
1
902 770
1F°
3
905 370
1P°
1
914 500
2s22p3(4S)4s
3S°
1
910 750
2s2p4(4P)3s
3P
2
940 450
1
941 940
0
942 630
2s22p3(2D)4s
3D°
3
962 070
2
962 100
1
962 110
2s22p3(4S)4d
3D°
1,2
962 410
3
962 450
2s22p3(2D)4s
1D°
2
964 840
(2P)4s
1P°
1
993 350
2s22p3(4S)5s
3S°
1
1 002 130
2s22p3(2D)4d
3D°
3
1 013 840
2
1 013 900
1
1 013 930
1P°
1
1 015 620
3P°
2
1 017 620
1
1 018 000
1D°
2
1 018 430
1F°
3
1 019 500
2s2p4(2D)3s
3D
1
1 020 350
2
1 020 420
3
1 020 520
2s22p3(4S)5d
3D°
1,2,3
1 026 780
2s22p3(2P)4d
3P°
1
1 042 570
2
1 042 800
3D°
1,2,3
1 043 860
1F°
3
1 045 350
2s2p4(4P)3d
3D
1,2,3
1 075 090
(2D)3d
3D
3
1 166 530
2
1 166 590
1
1 166 650
TABLE III
Parameter values for the interacting 2s2p5, 2s22p33s, and 2s22p33d configurations of Mg4+ and comparison with HF values.
Fitted value of this parameter was held equal to that of ζ2p of 2p33d.
Ratio of R1(2p2p,2s3d) to R1(2p2p,2s3s) was fixed at the value derived from the HF calculation.
Ratio of R2(2p3d,2p3s) to R1(2p3d,3s2p) was fixed at the value derived from the HF calculation.
TABLE IV
Departures from LS coupling in the J = 1 and J = 2 levels of 2s22p3(2D)3d and 2s22p3(2P)3d. All other levels of 2s2p5, 2s22p33s, and 2s22p33d have LS purities greater than 96%. Energy units are cm−1.
This level was omitted from the parametric fit; the calculated value was 877 601 cm−1, 1914 cm−1 lower than the observed value.
This level also has 8.5% of (2D) 1D.
Uncertainty on the measured wavelengths is estimated to be ±0.005 Å.
Intensities are visual estimates, (af indicates that a close line affected the measurement.)
The line at 97.440 Å was previously1 classified as 2p43P2–2s2p4(4P)3p3D3, the other transitions of the multiplet being blended with Mg viii (97.606 and 97.686 Å). This identification is rejected because the resulting level at 1 026 270 cm−1 would be much higher than the predicted position for 2s2p4(4P)3p levels.
This line was observed but not classified by Söderqvist.1 Kelly and Palumbo6 reported the lines 99.610 and 99.788 Å as 2p43P2,1–2p3(4S)5s3S1 transitions. This would locate the 2p3(4S)5s3S1 level at 1 003 900 cm−1, but this value is not consistent with the expected quantum-defect variation. Therefore, Söderqvist’s identification1 of 2p3(4S)5s3S1 at 1 002 130 was preferred. The level at 1 003 900, if real, may possibly be 2s2p4(4P)3p3D.
For these lines, we give the wavelengths of Johannesson et al.2 which we confirmed within ±0.003 Å.
The identification of this line was established by Fawcett et al.3
TABLE II
Energy levels of Mg4+.
Configuration and parent
Term
J
Level (cm−1)
2s22p4
3P
2
0.0
1
1 783.1
0
2 521.8
1D
2
35 926
1S
0
77 279
2s2p5
3P°
2
283 212.3
1
284 828.3
0
285 712.0
1P°
1
397 482
2p6
1S
0
662 970
2s22p3(4S)3s
3S°
1
684 540
(2D)3s
3D°
3
727 740
2
727 760
1
727 780
1D°
2
735 550
(2P)3s
3p°
0
756 550
1
756 570
2
756 640
1P°
1
764 630
2s22p3(4S)3d
3D°
1
821 970
2
821 990
3
822 070
(2D)3d
3D°
3
871 220
2
871 360
1
871 390
1P°
1
873 460
3P°
2
876 790
1
877 280
0
877 460
1D°
2
877 610
3S°
1
879 510
1F°
3
882 790
(2P)3d
3P°
0
898 760
1
898 960
2
899 370
1D°
2
901 470
3D°
3
902 150
2
902 510
1
902 770
1F°
3
905 370
1P°
1
914 500
2s22p3(4S)4s
3S°
1
910 750
2s2p4(4P)3s
3P
2
940 450
1
941 940
0
942 630
2s22p3(2D)4s
3D°
3
962 070
2
962 100
1
962 110
2s22p3(4S)4d
3D°
1,2
962 410
3
962 450
2s22p3(2D)4s
1D°
2
964 840
(2P)4s
1P°
1
993 350
2s22p3(4S)5s
3S°
1
1 002 130
2s22p3(2D)4d
3D°
3
1 013 840
2
1 013 900
1
1 013 930
1P°
1
1 015 620
3P°
2
1 017 620
1
1 018 000
1D°
2
1 018 430
1F°
3
1 019 500
2s2p4(2D)3s
3D
1
1 020 350
2
1 020 420
3
1 020 520
2s22p3(4S)5d
3D°
1,2,3
1 026 780
2s22p3(2P)4d
3P°
1
1 042 570
2
1 042 800
3D°
1,2,3
1 043 860
1F°
3
1 045 350
2s2p4(4P)3d
3D
1,2,3
1 075 090
(2D)3d
3D
3
1 166 530
2
1 166 590
1
1 166 650
TABLE III
Parameter values for the interacting 2s2p5, 2s22p33s, and 2s22p33d configurations of Mg4+ and comparison with HF values.
Fitted value of this parameter was held equal to that of ζ2p of 2p33d.
Ratio of R1(2p2p,2s3d) to R1(2p2p,2s3s) was fixed at the value derived from the HF calculation.
Ratio of R2(2p3d,2p3s) to R1(2p3d,3s2p) was fixed at the value derived from the HF calculation.
TABLE IV
Departures from LS coupling in the J = 1 and J = 2 levels of 2s22p3(2D)3d and 2s22p3(2P)3d. All other levels of 2s2p5, 2s22p33s, and 2s22p33d have LS purities greater than 96%. Energy units are cm−1.
This level was omitted from the parametric fit; the calculated value was 877 601 cm−1, 1914 cm−1 lower than the observed value.
This level also has 8.5% of (2D) 1D.