wilkinson_1960 ============== P\. G\. Wilkinson, J\. Opt\. Soc\. Am\. 50, 1002 \(1960\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1364/josa\.50\.001002 `__ **Source kind:** measurement **Recorded technique:** Refractive line shifts in a 21 ft vacuum Eagle concave\-grating spectrograph \(third order, resolving power about 270 000, 0\.4 A/mm\) filled with nitrogen\: a germanium hollow\-cathode line spectrum photographed in vacuum and then in the gas without moving the plate; n \- 1 = Delta lambda / lambda\_g \(Eq\. 2\)\. An instrumental \(mechanical strain\) shift appears when gas is admitted; it is measured on second\-order lines whose index is calculated from Koch's data \(Eq\. 5\) and removed \(Eq\. 6\)\. Gas temperature to 0\.03 C, pressure to 0\.01 mm \(mercury manometer, reduced to standard gravity and 0 C\)\. Matheson nitrogen with O2 about 2e\-4 % and CO 1e\-5 % \(pp\. 1\-2\)\. **Materials in structured entries:** N2 **Dataset quantities:** refractivity **Contents:** 1 dataset; 2 formulas. Curation notes -------------- 'Refractive indices are then obtained at standard conditions \(0 C and 760 mm\)\. The use of the perfect gas law is valid within the accuracy of the measurements' \(p\. 2\)\: state 1 atm, 0 C, density ideal\. Wavelengths are vacuum wavelengths \(Table II heading\)\. The oxygen impurity limited the measurements to 1649 A and longer \(Schumann\-Runge absorption\)\. Accuracy\: 'The data fit the following equation to \+\-0\.13%' \(abstract\), which is the mean absolute obs \- calc of Table II \(4\.7 x 10^\-7 against n \- 1 of about 3\.5 x 10^\-4\); the rms of the printed obs \- calc, 5\.9 x 10^\-7, is taken as the per\-point uncertainty\. 'The data are too inaccurate' for the resonance parameters to be meaningful \(p\. 4\)\. The absolute level rests on the instrumental\-shift correction, which uses Koch's refractive indices at 2398\-3058 A \(Eq\. 5\)\. Heddle et al\. \(heddle\_1963\) and Langhoff and Karplus \(langhoff\_1969\) suspect oxygen contamination in the values near 1650\-1750 A, which lie above their calculations\. Reproductions\: langhoff\_1969 \(Table V, dataset wilkinson\_1960\_N2\) reproduces all 22 values, identically but for 1938\.89 A, printed there 3\.445 x 10^\-4 against the original's 3455 x 10^\-7 \(Table II image checked\: 3455\)\. It should now be marked reproduced of this record\. heddle\_1963 \(wilkinson\_formula\_N2\) and peck\_1966 \(formula wilkinson\_1960\) reproduce Eq\. \(7\)\. Koch's formula \(Eq\. 8\), quoted for comparison, is recorded as a reproduced formula\. **Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- wilkinson\_1960/experiment\_N2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "experiment_N2", "material": "N2", "file": "N2/wilkinson_1960__experiment_N2.csv", "table": "tbl_12497a3674f3", "quantity": "refractivity", "scale": 1e-07, "abscissa_unit": "angstrom", "wavelength_medium": "vacuum", "state": "1atm_0C", "density": "ideal", "use": "primary", "uncertainty": { "absolute": 5.9, "level": "rms" } } Table II, \(n \- 1\) x 10^7 at 0 C and 760 mm, 22 lines of Ge I, Ge II, Ne II and one unidentified emitter \('?', 2042\.484 A\)\. Per\-point uncertainty\: the rms of the printed obs \- calc \(5\.9 x 10^\-7\)\. Formulas -------- wilkinson\_1960/eq7 ~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "eq7", "material": "N2", "equation": "Eq. (7), p. 3 (also the abstract)", "printed": "n - 1 = 6.3622 x 10^4 / (45.989 x 10^8 - nu^2) + 32.453 x 10^6 / (1065.11 x 10^8 - nu^2)", "variable": "nu: vacuum wavenumber in cm^-1", "state": "1atm_0C", "density": "ideal", "range": "1649-2042 A (vacuum)", "coefficients": { "B1": "6.3622e4", "C1": "45.989e8", "B2": "32.453e6", "C2": "1065.11e8" }, "check": "Reproduces Table II's obs - calc column to within 1.1 x 10^-7 at 19 of the 22 lines; at 1938.890 A it gives +1.9 against the printed +7 (the reproduction's 3.445 would give -8.1), at 1824.2994 A +3.5 against +1, and at 1649.1918 A -11.7 against -3. Resonances at 1474.6 and 306.4 A with oscillator strengths 0.053 and 27 (p. 4), 'which have no real significance'. Checked 2026-09-25." } wilkinson\_1960/koch\_eq8 ~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "koch_eq8", "material": "N2", "equation": "Eq. (8), p. 3", "printed": "n - 1 = 39.5345 x 10^5 / (152.274 x 10^8 - nu^2) + 8.3734 x 10^5 / (240.651 x 10^8 + nu^2)", "variable": "nu: vacuum wavenumber in cm^-1 (presumably, as Eq. 7)", "state": "1atm_0C", "density": "unknown", "range": "2380-5460 A", "coefficients": { "B1": "39.5345e5", "C1": "152.274e8", "B2": "8.3734e5", "C2": "240.651e8" }, "reproduced_from": [ "J. Koch, Arkiv Mat. 8, No. 20 (1912); 9, No. 6 (1913); 10, No. 1 (1914); 18, No. 3 (1924)" ], "check": "Gives 3397.8 x 10^-7 at 2042.484 A and 3724.5 at 1649.19 A (extrapolated), below the present data as Fig. 2 shows. Not checked against Koch's values (not in the library). Checked 2026-09-25." } The '\+ nu^2' in the second denominator is as printed; Wilkinson remarks that 'Eq\. \(8\) is not of the proper form owing to inclusion of a \+ nu^2 term in the denominator of the second term' \(p\. 3\)\. 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.