ciddor_2002

P. E. Ciddor, Appl. Opt. 41, 2292 (2002)

Source record · Catalogue · Review register

No DOI is recorded.

Source kind: compilation

Recorded technique: Review and recalculation of the refractive index of moist air (three components: CO2-free dry air, CO2, water vapour), combined by Lorentz-Lorenz terms (Eqs. 6-9); no measurements.

Materials in structured entries: CO2

Dataset quantities: None recorded.

Contents: 0 datasets; 2 formulas.

Curation notes

The library record is unverified; the title and author are from the page (‘Refractive index of air: 3. The roles of CO2, H2O, and refractivity virials’, P. E. Ciddor, CSIRO; received 6 August 2001; footer 0003-6935/02/122292-07); volume and page as cited by marchetti_2006’s reference list (Appl. Optics 41 (2002) 2292-2298). No DOI.

Nothing is extracted as data. The CO2 dispersion equations the paper compares are recorded as reproduced formulas (Eq. 4, Edlen’s; Eq. 5, Old et al.’s, curated as old_1971). Table 1 (air densities and phase and group refractivities) and Table 2 (experimental limits) concern air, not a curated species; the water-vapour discussion (Barrell and Sears’s reference refractivity, revised to 308.7 at 10 mm Hg, 20 C, x 10^-8, 1.005 times Owens’s 307.1) likewise.

Refractivity virials (Section 8): no values are given. Quoted: ‘the second refractivity virial coefficient for N2 is variously quoted [refs. 16-18: achtermann_1991, Montixi et al. 1983, Burns et al. 1986] with a relative uncertainty of ~10%’, and for N2 (from Achtermann et al.) B_R rho0 / A_R ~ 8 x 10^-6 at atmospheric density, so that the linear approximation L* = A_R* rho errs by 6e-10 in n within 20 % of the reference density. The paper also states that the Old et al. equation (with the 4.2 um CO2 resonance) extrapolates well into the infrared whereas Edlen’s does not, the two differing by less than 3e-7 at about 500-700 nm and by less than 5e-6 in the near infrared (Fig. 1).

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets

No datasets are recorded.

Formulas

ciddor_2002/edlen_co2

{
  "id": "edlen_co2",
  "material": "CO2",
  "equation": "Eq. (4), p. 2",
  "printed": "10^8 (n_EDLEN - 1) = 22822.1 + 117.8 sigma^2 + 2406030/(130 - sigma^2) + 15997/(38.9 - sigma^2)",
  "variable": "sigma = 1/lambda, lambda the vacuum wavelength in micrometres",
  "state": "1atm_15C",
  "density": "unknown",
  "range": "about 250-700 nm (Edlen's CO2 data)",
  "coefficients": {
    "A": "22822.1",
    "B": "117.8",
    "C1": "2406030",
    "D1": "130",
    "C2": "15997",
    "D2": "38.9"
  },
  "reproduced_from": [
    "edlen_1966",
    "C. and M. Cuthbertson, Proc. R. Soc. London A 97, 152 (1920) (cuthbertson_1920)",
    "J. Koch (1914)"
  ],
  "check": "Stated to be 'at a common temperature of 0 C and CO2 pressure of 101,325 Pa', but at 633 nm it gives 42426e-8, while Eq. (5) (Old et al., 0 C) gives 44794e-8; scaled by 288.15/273.15 it gives 44756e-8, 3.8e-7 below Eq. (5); over 500-700 nm the scaled Eq. (4) lies 3.1-4.3e-7 below Eq. (5), close to but not within the text's 'less than 3 x 10^-7'. The scaling is settled instead by Fig. 2, which the scaled Eq. (4) reproduces (zero crossing at 864 nm, +0.069 at 1300 nm), as it does Fig. 1 (second reading, 2026-09-25; TC-157). The printed coefficients are therefore Edlen's 15 C air formula (edlen_1966: 2406030/(130 - s^2) + 15997/(38.9 - s^2)) plus his CO2 correction (14485 + 117.8 s^2, eq18_CO2), i.e. for 15 C, not 0 C; the constant 22822.1 is 5.0 below 8342.13 + 14485 (not explained in the paper). The state recorded is 15 C accordingly. Checked 2026-09-25."
}

Represents ultraviolet resonances only; ‘valid only in the ultraviolet and the visible’ (abstract).

ciddor_2002/old_co2

{
  "id": "old_co2",
  "material": "CO2",
  "equation": "Eq. (5), p. 2",
  "printed": "10^8 (n_OLD - 1) = 154.489/(0.0584738 - sigma^2) + 8309192.7/(210.92417 - sigma^2) + 287641.90/(60.122959 - sigma^2)",
  "variable": "sigma = 1/lambda, lambda the vacuum wavelength in micrometres",
  "state": "1atm_0C",
  "density": "real",
  "range": "480-1817 nm (Old et al.'s measurements)",
  "coefficients": {
    "B1": "154.489",
    "C1": "0.0584738",
    "B2": "8309192.7",
    "C2": "210.92417",
    "B3": "287641.90",
    "C3": "60.122959"
  },
  "reproduced_from": [
    "old_1971"
  ],
  "check": "Identical to old_1971's Sellmeier (x 10^5 there, every numerator 1000 times smaller); 44794e-8 at 633 nm. Checked 2026-09-25."
}

The first term is the 4.2 um infrared resonance. Ciddor adopts it as the standard for CO2.

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.