ityaksov_2008_co2 ================= D\. Ityaksov, H\. Linnartz and W\. Ubachs, Chem\. Phys\. Lett\. 462, 31 \(2008\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1016/j\.cplett\.2008\.07\.049 `__ **Source kind:** measurement **Recorded technique:** Cavity ring\-down extinction with pressure ramps from 0 to 10^5 Pa at room temperature \(pressure to 0\.15 %\), laser bandwidth below 0\.2 cm^\-1; 40 cm cell for 215\-270 nm, the 82 cm turbulence\-free cell for 198\-204 nm \(pp\. 2\-3\)\. CO2 99\.7 %\. **Materials in structured entries:** CO2 **Dataset quantities:** rayleigh\_cross\_section **Contents:** 2 datasets; 3 formulas. Curation notes -------------- CO2 was deferred when this record was written \(every dataset "check"\); the CO2 was taken up on 2026\-09\-25, so the measured extinction is primary like any other gas's data \(the calculated column stays a check\)\. The measured quantity is the extinction cross section per molecule, Rayleigh scattering plus absorption; below about 202 nm CO2 absorbs \('the onset actually starts at higher energy, around 202 nm', abstract\), and the paper's Rayleigh fit is restricted to 202\-300 nm\. The rows below 202 nm are therefore excluded from the Rayleigh dataset \(kept in its file\)\. 'The experimental error \(1 sigma uncertainty\) is ~15% for the measurements in the 215\.38\-270\.15 nm interval and about 10% for observations in the wavelength region where the turbulence free CRD cell has been used' \(p\. 2\); the table's \+\- are the per\-point one\-sigma values\. No quadratic density dependence \(collision\-induced effects\) was found\. Wavelengths are vacuum \(Eqs\. 3\-4, 'the wavelength lambda \(in vacuum\)'\)\. The calculated cross sections use Eq\. \(2\) with 'the dispersion formulas for the refractive indices \[9\] and depolarization ratios \[10\]' at 288\.15 K and 101 325 Pa\. Check \(2026\-09\-25\)\: with N = 2\.5469e19 cm^\-3, the refractive\-index formula of sneep\_2005 \(Eq\. 13, scale read as 1\.1427 x 10^3\) and its King factor \(Eq\. 14, 1\.1364 \+ 25\.3e\-12 nu^2\) every one of the 22 calculated values is reproduced to its printed 0\.1; with this paper's rounded Eqs\. \(3\) and \(4\) they come out up to 0\.08 higher\. Eq\. \(4\) repeats sneep\_2005's misprinted scale 1\.1427 x 10^6 \(it must be 10^3\)\. The literature data of Figs\. 1\-3 \(Shemansky, Ogawa, Karaiskou et al\., Parkinson et al\., Lewis and Carver, Sneep et al\., Dong and Gupta\) are not tabulated here\. **Recorded bibliographic identity status:** VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- ityaksov\_2008\_co2/extinction\_CO2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "extinction_CO2", "material": "CO2", "file": "CO2/ityaksov_2008_co2__extinction_CO2.csv", "table": "tbl_d53eeed0ae27", "quantity": "rayleigh_cross_section", "unit": "cm2", "scale": 1e-25, "abscissa_unit": "nm", "wavelength_medium": "vacuum", "use": "primary", "excluded_rows": { "197.70": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "197.84": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "198.28": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "198.38": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "198.48": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "198.75": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "199.10": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "199.55": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "199.90": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "200.08": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "200.42": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "200.76": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "201.00": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "201.33": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "201.58": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption", "201.78": "below the absorption onset near 202 nm: the extinction includes CO2 photoabsorption" }, "uncertainty": { "column": true, "level": "1 sigma" } } Table 1, measured extinction cross section, \+\- one sigma\. Rows from 202\.43 nm on are Rayleigh scattering \(the paper's fit range 202\-300 nm\); 201\.78 nm \(8\.0 \+\- 1\.2\) lies below the calculated 9\.1 and is excluded with the absorbing rows by the paper's onset\. Deferred gas\: check\. ityaksov\_2008\_co2/calculated\_CO2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "calculated_CO2", "material": "CO2", "file": "CO2/ityaksov_2008_co2__calculated_CO2.csv", "table": "tbl_d53eeed0ae27", "quantity": "rayleigh_cross_section", "unit": "cm2", "scale": 1e-25, "abscissa_unit": "nm", "wavelength_medium": "vacuum", "use": "check" } Table 1, sigma\_R^calc from Bideau\-Mehu et al\.'s refractive index and Alms et al\.'s depolarization \(via sneep\_2005's Eqs\. 13 and 14; see the source notes\)\. Not a measurement\. Formulas -------- ityaksov\_2008\_co2/king\_eq3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "king_eq3", "material": "CO2", "equation": "Eq. (3), p. 2", "printed": "F_k(lambda) = 1.14 + 25.3 x 10^-12 / lambda^2", "variable": "lambda: vacuum wavelength in cm", "range": "not stated (sneep_2005's fit to Alms et al., 4579-6471 A)", "coefficients": { "a": "1.14", "b": "25.3e-12" }, "reproduced_from": [ "sneep_2005" ], "check": "sneep_2005's Eq. (14) with 1.1364 rounded to 1.14; the calculated column follows the unrounded form (see the source notes). Checked 2026-09-25." } ityaksov\_2008\_co2/n\_eq4 ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "n_eq4", "material": "CO2", "equation": "Eq. (4), p. 2", "printed": "n(lambda) - 1 = 1.1427 x 10^6 (5799.3 lambda^2/(16.6 x 10^9 lambda^2 - 1) + 120 lambda^2/(7.96 x 10^9 lambda^2 - 1) + 5.33 lambda^2/(5.63 x 10^9 lambda^2 - 1) + 4.32 lambda^2/(4.6 x 10^9 lambda^2 - 1) + 1.22 x 10^-5 lambda^2/(5.85 x 10^6 lambda^2 - 1))", "variable": "lambda: vacuum wavelength in cm", "state": "1atm_15C", "density": "ideal", "range": "180-254 nm (Bideau-Mehu et al.'s data, as stated p. 3)", "coefficients": { "scale": "1.1427e6", "B1": "5799.3", "C1": "16.6e9", "B2": "120", "C2": "7.96e9", "B3": "5.33", "C3": "5.63e9", "B4": "4.32", "C4": "4.6e9", "B5": "1.22e-5", "C5": "5.85e6" }, "reproduced_from": [ "sneep_2005", "A. Bideau-Mehu, Y. Guern, R. Abjean and A. Johannin-Gilles, Opt. Commun. 9, 432 (1973)" ], "check": "sneep_2005's Eq. (13) rewritten with the poles squared and rounded (128908.9^2 = 1.6617e10 -> 16.6e9, ...). The scale 1.1427 x 10^6 gives n - 1 = 0.5 at 200 nm; with 10^3, 501.7e-6 at 197.7 nm. Checked 2026-09-25." } ityaksov\_2008\_co2/power\_eq6 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "power_eq6", "material": "CO2", "equation": "Eq. (6), p. 3", "printed": "sigma_R = sigma_bar nu^(4 + epsilon); sigma_bar = 1.78(7) x 10^-46, epsilon = 0.625(3)", "variable": "nu: vacuum wavenumber in cm^-1; sigma_R in cm^2", "range": "202-300 nm (fitted to this work's and the literature's data except Ogawa's); 'not meant to be extrapolated beyond 300 nm', 20 % off at 532 nm", "coefficients": { "sigma_bar": "1.78e-46", "epsilon": "0.625" }, "check": "Gives 9.10, 6.83, 2.39 x 10^-25 cm^2 at 202.43, 215.38, 270.15 nm against the measured 7.9 +- 0.8, 6.6 +- 1.0, 2.3 +- 0.4 and calculated 9.0, 6.7, 2.4. Checked 2026-09-25." } 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.