Measurements have been made on about 200 Si i lines in the region 1548 to 2000 Å excited by a low-pressure source, resulting in wavelength values with uncertainties of less than 0.0015 Å on the average. Of these vacuum ultraviolet wavelengths, 88 have been calculated by Radziemski and Andrew [
J. Opt. Soc. Am. 55,
474 (
1965)], and a comparison of measured and calculated values gives an average deviation of 0.0008 Å. A plot of the differences shows the scatter to be much greater than any systematic difference. This indicates that the calculated wavelengths are compatible with the set of Ge i lines used as standards in measuring the Si i lines. The new data have also led to an extension and a slight revision of the odd-level analysis. New measurements on some lines of C i, Ge ii, N i, and Si ii are also reported. Spectrograms were taken in the first order on a 10.7-m Eagle vacuum spectrograph with a reciprocal dispersion of 0.78 Å/mm. The source was an electrodeless discharge lamp containing SiCl4 and GeCl4 vapor with argon or helium carrier gas at a total pressure no greater than 0.5 torr.
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The figures in this column are visual estimates of plate blackening relative to 1988 Å which was assigned the intensity 1000.
Values in this column are taken from Table VI of Ref. 1.
The numbers in this column are the code numbers for the levels given in Tables III and IV, Ref. 1 and Table II of this paper. The “°” symbol designates an odd level.
This line is partially masked by a strong Ge ii line at 1576.852 Å.
This line fits well the transition 4–69° but since the previous member of the series was missing the coincidence was taken to be accidental.
This line is within 0.002 Å of a Ge i line.
This line is within 0.04 Å of a strong Ge i line.
These are averages of grating and interferometric values. The latter values are those of Table II, Ref. 1, lowered by about 0.003 Å (prior to averaging) because of a change in the phase correction curve in this region.
A parenthesis about a level value indicates that the level has been established by a single combination. Hence, it should be considered provisional.
This level was first identified by Wilson.3
The line 64018.31 cm−1 which we here identify as 3p23P0–3p8d1P1° was also observed by Wilson3 but not classified. Instead he chose as this transition the line 64043.92 cm−1 which we did not observe.
Table III
Relative intensities of the Ge i vuv standards as they appear in the electrodeless lamp.
Except when indicated otherwise the uncertainty estimates in this column range from 0.0002 Å to 0.0007 Å with an average value of 0.0003 Å. The individual estimates for each entry are given in Ref. 4.
This wavelength did not appear in Ref. 4; this experimental value is from this investigation and its estimated uncertainty is 0.0010 Å.
Corrected value. Through a copying error this was listed in Ref. 4 as σ 51613.374 cm−1 with corresponding wavelength λ 1937.48233 Å whereas it should have been σ 51613.370 cm−1 with corresponding wavelength λ 1937.48248 Å.
Table IV
Newly measured auxiliary standards in the near vacuum ultraviolet.
The estimated uncertainty in these values is ±0.0010 Å.
See Ref. 5.
These are calculated wavelengths reported in Ref. 6.
This is vacuum wavelength, even though the wave number is less than 50000 cm−1.
The figures in this column are visual estimates of plate blackening relative to 1988 Å which was assigned the intensity 1000.
Values in this column are taken from Table VI of Ref. 1.
The numbers in this column are the code numbers for the levels given in Tables III and IV, Ref. 1 and Table II of this paper. The “°” symbol designates an odd level.
This line is partially masked by a strong Ge ii line at 1576.852 Å.
This line fits well the transition 4–69° but since the previous member of the series was missing the coincidence was taken to be accidental.
This line is within 0.002 Å of a Ge i line.
This line is within 0.04 Å of a strong Ge i line.
These are averages of grating and interferometric values. The latter values are those of Table II, Ref. 1, lowered by about 0.003 Å (prior to averaging) because of a change in the phase correction curve in this region.
A parenthesis about a level value indicates that the level has been established by a single combination. Hence, it should be considered provisional.
This level was first identified by Wilson.3
The line 64018.31 cm−1 which we here identify as 3p23P0–3p8d1P1° was also observed by Wilson3 but not classified. Instead he chose as this transition the line 64043.92 cm−1 which we did not observe.
Table III
Relative intensities of the Ge i vuv standards as they appear in the electrodeless lamp.
Except when indicated otherwise the uncertainty estimates in this column range from 0.0002 Å to 0.0007 Å with an average value of 0.0003 Å. The individual estimates for each entry are given in Ref. 4.
This wavelength did not appear in Ref. 4; this experimental value is from this investigation and its estimated uncertainty is 0.0010 Å.
Corrected value. Through a copying error this was listed in Ref. 4 as σ 51613.374 cm−1 with corresponding wavelength λ 1937.48233 Å whereas it should have been σ 51613.370 cm−1 with corresponding wavelength λ 1937.48248 Å.
Table IV
Newly measured auxiliary standards in the near vacuum ultraviolet.
The estimated uncertainty in these values is ±0.0010 Å.
See Ref. 5.
These are calculated wavelengths reported in Ref. 6.
This is vacuum wavelength, even though the wave number is less than 50000 cm−1.