The absorption spectrum of atomic argon below 1000 Å has been investigated with a 6.65-m vacuum spectrograph and with the helium continuum for background. The expected five ns and nd Rydberg series have been extended as far as lines with n about 50 and greater. The ionization energies obtained are 127 109.9±0.1 cm−1 and 128 541.8±0.3 cm−1 for
and
states of Ar ii, respectively. Strong interactions between nd and nd′ series are observed as perturbations and autoionizations. Six additional (weak) Rydberg series are identified as electric-quadrupole transitions to 3p5np and 3p5nf levels.
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Estimated relative intensity measured from densitometer traces here and throughout. The n=3 line in Table II is taken as I=100, the strongest line in the region below 1000 Å.
See Ref. 1 here and throughout.
Superimposed upon the 13d(3/2)1°, see Table II.
Member lines with n≧22 are not resolved from n≧20 lines of the nd(3/2)1° series, respectively.
Strongly perturbed line.
Superimposed upon the 15s(3/2)1° line.
Member lines with n≧20 are unresolved from n≧22 lines of the ns(3/2)1° series, respectively.
These are slightly less accurate than others and are not included in the series-limit calculation.
This is the strongest line in the region below 1000 Å.
No previous value is available, see Ref. 1.
Strongly perturbed line.
Member lines with n>24 are not resolved from n>22 lines of the nd′(3/2)1° series, respectively.
No previous value is available, see Ref. 1.
Difference from Hudson and Carter’s resolved lines with 11≦n≦14.
Difference from Hudson and Carter’s unresolved lines with n≧15.
The lines with n>8 appear very diffuse, owing to autoionization. The peak intensities of such lines can not be compared with those of sharp lines (see Table XIII).
No previous value is available, see Ref. 1.
Difference from Hudson and Carter’s resolved lines with 9≦n≦12.
Difference from Hudson and Carter’s unresolved lines with n≧13.
Argon pressure for which the strongest line of the series becomes noticeable on a plate. Estimation was made with room-temperature argon, a 13-m path length, and the same conditions for Table VI–XI.
Roughly the same scale as for lines in previous tables.
The member lines with n>8 cannot be observed, because the region where these are expected is completely absorbing, owing to the ionization continuum associated with the Ar ii2P3/2° state and the autoionized lines.
Diffuse structure associated with the member lines. The diffuse structures for n>8 are too close to be measured.
Superimposed upon the 8d(3/2)1° line.
Superimposed upon the
line.
Too close to be separated from the corresponding nf(5/2)2 lines.
Diffuse structures associated with member lines.
Superimposed upon the 14s(3/2)1° line. The lines with n≧8 cannot be observed, because the expected region is totally absorbing, owing to the autoionized lines and the ionization continuum associated with the Ar ii2P3/2° state.
Table XII
Interaction parameter α (cm−1)a for series perturbation.
Estimated relative intensity measured from densitometer traces here and throughout. The n=3 line in Table II is taken as I=100, the strongest line in the region below 1000 Å.
See Ref. 1 here and throughout.
Superimposed upon the 13d(3/2)1°, see Table II.
Member lines with n≧22 are not resolved from n≧20 lines of the nd(3/2)1° series, respectively.
Strongly perturbed line.
Superimposed upon the 15s(3/2)1° line.
Member lines with n≧20 are unresolved from n≧22 lines of the ns(3/2)1° series, respectively.
These are slightly less accurate than others and are not included in the series-limit calculation.
This is the strongest line in the region below 1000 Å.
No previous value is available, see Ref. 1.
Strongly perturbed line.
Member lines with n>24 are not resolved from n>22 lines of the nd′(3/2)1° series, respectively.
No previous value is available, see Ref. 1.
Difference from Hudson and Carter’s resolved lines with 11≦n≦14.
Difference from Hudson and Carter’s unresolved lines with n≧15.
The lines with n>8 appear very diffuse, owing to autoionization. The peak intensities of such lines can not be compared with those of sharp lines (see Table XIII).
No previous value is available, see Ref. 1.
Difference from Hudson and Carter’s resolved lines with 9≦n≦12.
Difference from Hudson and Carter’s unresolved lines with n≧13.
Argon pressure for which the strongest line of the series becomes noticeable on a plate. Estimation was made with room-temperature argon, a 13-m path length, and the same conditions for Table VI–XI.
Roughly the same scale as for lines in previous tables.
The member lines with n>8 cannot be observed, because the region where these are expected is completely absorbing, owing to the ionization continuum associated with the Ar ii2P3/2° state and the autoionized lines.
Diffuse structure associated with the member lines. The diffuse structures for n>8 are too close to be measured.
Superimposed upon the 8d(3/2)1° line.
Superimposed upon the
line.
Too close to be separated from the corresponding nf(5/2)2 lines.
Diffuse structures associated with member lines.
Superimposed upon the 14s(3/2)1° line. The lines with n≧8 cannot be observed, because the expected region is totally absorbing, owing to the autoionized lines and the ionization continuum associated with the Ar ii2P3/2° state.
Table XII
Interaction parameter α (cm−1)a for series perturbation.