watanabe_1953#
K. Watanabe, E. C. Y. Inn and M. Zelikoff, “Absorption coefficients of oxygen in the vacuum ultraviolet”, J. Chem. Phys. 21, 1026 (1953)
Source record · Catalogue · Review register
DOI: 10.1063/1.1699104
Source kind: measurement
Recorded technique: Photoelectric absorption: windowless hydrogen discharge (many-line spectrum below about 1650 A, continuum above), Baird 1 m normal-incidence vacuum monochromator with 0.05 mm slits (band width 0.85 A), scanned at 20 A/min, wavelengths to the nearest angstrom (‘occasionally ... in error by as much as two angstroms’); a Pyrex cell 4.7 cm long with LiF windows behind the exit slit; a sodium-salicylate-coated 1P21 photomultiplier; O2 at 0.1-500 mm Hg (impurity about 0.1 %, mostly N2); scattered light and LiF fluorescence corrected; several pressures differing by at least ten at each of several hundred wavelengths, 1050-1900 A (pp. 1026-1027).
Materials in structured entries: O2
Dataset quantities: absorption_cross_section, oscillator_strength
Contents: 3 datasets; 0 formulas.
Curation notes#
Journal pages 1026-1030 = PDF pages 2-6 (page 1 is the publisher’s cover). O2 only. The absorption coefficients are given only in figures (Fig. 3: the Schumann-Runge bands 1750-1950 A; Fig. 4: the Schumann-Runge continuum 1300-1750 A, ‘the mean of several hundred points’; Fig. 5: 1050-1300 A); no table of k. What the text states is recorded as points.
Quantity (p. 1027): ‘The absorption coefficient, k in cm^-1, is defined by I/I0 = exp(-kx) where x is the layer thickness of the absorbing gas reduced to NTP’ (NTP not defined further; taken as 0 C and 1 atm, as Weissler and Lee define it and as Metzger and Cook’s Loschmidt number implies). No conversion to cross sections is given; the datasets store k with scale = 1e18 / n0, n0 = 101325 Pa / (k_B 273.15 K) = 2.6867801e19 cm^-3 (ideal gas), to the cross section in Mb. ‘photoionization_cross_section’ is used for want of a photoabsorption cross section (all these wavelengths are below the O2 ionisation limit; format need reported).
Reliability as stated: in the Schumann-Runge bands (1750-1900 A) ‘the resolution was not adequate to resolve the P and R branches’; the ‘observed coefficients’ vary with pressure by a factor of four or five over a factor of 70 in pressure (‘the head of the 14-0 band was 4.0 cm^-1 at a pressure of 7.1-mm Hg and 0.9 cm^-1 at 491 mm’, p. 1028); Fig. 3 is smoothed (‘maxima are probably still too low and minima too high’). k below 0.02 cm^-1 could not be measured; the lowest band seen is 4-0. In the continuum ‘Within experimental error (about 5 percent) Beer’s Law held over a pressure range of a factor of twenty’ (p. 1029); the Shell Oil laboratory’s measurement agreed in 1750-1570 A. Below 1170 A Fig. 5 is ‘semiquantitative’; 1170-1300 A ‘should be fairly reliable’ (p. 1030).
Text values not taken as data (pp. 1028-1030): at Lyman alpha 0.30 cm^-1 at 70 mm and 0.50 cm^-1 at 490 mm (pressure effect; the zero-pressure value 0.27 is the dataset); Preston’s (1940) extrapolated 0.28 cm^-1 (reproduced; Metzger and Cook’s window 1 also 0.28); a weak continuum at 1105 A of ‘order of 1 cm^-1 in Fig. 5’, against Weissler and Lee’s 50-100 cm^-1; Weissler and Lee’s 7 values in 1060-1170 A ‘in general, considerably larger’; Ladenburg and Van Voorhis’s maximum about 490 cm^-1 at 1450 A (reproduced). Also: the dissociation limit of B 3Sigma_u^- 57140 +- 60 cm^-1 (19-0 and 20-0 bands observed); Ladenburg and Wolfsohn’s dispersion resonance lambda_2 = 1468 A and Koch’s 1421 A (p. 1029).
Table I (tbl_a84e89715f1d, image checked): relative intensities of the Schumann-Runge bands 8-0 to 18-0 at 7.8 mm Hg, 12-0 = 100 (39, 42, 59, 90, 100, 87, 124, 146, 161, 166, 160), with Pillow’s theoretical 5-0 to 14-0 (1, 5, 20, 29, 51, 50, 78, 100, 90, 95). Not extracted: relative ‘observed’ intensities without pressure broadening, which Bethke (1959) shows are not proportional to the band strengths (his f(8,0)/f(12,0) = 0.24 against 0.39 here), and no vocabulary quantity.
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
watanabe_1953/lyman_alpha#
{
"id": "lyman_alpha",
"material": "O2",
"table": "text",
"quantity": "absorption_cross_section",
"unit": "Mb",
"scale": 0.03721927208,
"abscissa_unit": "angstrom",
"wavelength_medium": "vacuum",
"use": "primary"
}
1 inline points in the source record.
p. 1030: ‘Our extrapolated value was 0.27 cm^-1’ (k at zero pressure at Lyman alpha; 0.30 at 70 mm and 0.50 at 490 mm Hg). scale = 1e18 / n0 to Mb. The paper names the line, not its wavelength: 1215.7 A is Metzger and Cook’s Table 1 value for H Ly alpha (metzger_1964, p. 110). Uncertainty not stated. Metzger and Cook’s window 1 gives 0.28 cm^-1 at 1215.7 A.
watanabe_1953/sr_maximum#
{
"id": "sr_maximum",
"material": "O2",
"table": "text",
"quantity": "absorption_cross_section",
"unit": "Mb",
"scale": 0.03721927208,
"abscissa_unit": "angstrom",
"wavelength_medium": "vacuum",
"use": "primary",
"uncertainty": {
"relative": 0.05,
"level": "not stated"
}
}
1 inline points in the source record.
p. 1029: ‘The maximum in the present observation is rather flat and is 380 cm^-1 at about 1420A’ (the Schumann-Runge continuum, Fig. 4’s mean curve); scale = 1e18 / n0 to Mb. The wavelength is approximate (‘about’). 5 % from the stated ‘experimental error (about 5 percent)’ of the continuum measurements (level not stated). metzger_1964 gives 402 +- 20 cm^-1 at 1422 A.
watanabe_1953/sr_continuum_f#
{
"id": "sr_continuum_f",
"material": "O2",
"table": "text",
"quantity": "oscillator_strength",
"abscissa": "label",
"use": "check"
}
1 inline points in the source record.
p. 1030: f = (m c^2 / (N pi e^2)) integral k_nu dnu with nu1 = 5.7e4 and nu2 = 7.8e4 cm^-1: ‘the f value of 0.161 was obtained by integrating graphically the k value for the Schumann-Runge continuum’, against Ladenburg and Van Voorhis’s 0.193. Index abscissa: an integrated strength over the stated range. Compare metzger_1964 (0.142 over 5.71e4-7.41e4 cm^-1). A check.
Formulas#
No formulas are recorded.
Corrections#
No dataset errata are recorded in this source record.
Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.