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 `__ · :doc:`Catalogue ` · :doc:`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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 :doc:`review register ` for the checks and decisions.