schmidt_2003#
J. W. Schmidt and M. R. Moldover, “Dielectric Permittivity of Eight Gases Measured with Cross Capacitors”, Int. J. Thermophys. 24, 375 (2003)
Source record · Catalogue · Review register
Source kind: measurement
Recorded technique: Relative dielectric permittivity eps(p, T) from a four-ring toroidal cross capacitor (superinvar electrodes, sapphire-ball insulators; the capacitor, bridge, thermometers and pressure instruments of Moldover and Buckley 2001, ‘MB’), eps_expt = [C_x(p)/C_x(0)](1 + k_T p/3) with the measured superinvar compressibility k_T = (9.43 +- 0.38)e-12 Pa^-1 (Eq. 4); capacitance ratios with sub-ppm resolution (a commercial bridge). The deformation model is tested absolutely against the ab initio eps(p, T) of helium (<eps_expt - eps_theory> = (-0.05 +- 0.21)e-6, Fig. 3), and argon was measured simultaneously with a 16-rod stainless-steel cross capacitor (<eps_rod> - <eps_ring> = (0.161 +- 0.025)e-6 (p/MPa), 3e-5 A_eps of argon; Sect. 4). Isotherms at 0, 23, 29.3 and 40 degrees C (and MB’s 50 degrees C data, included in the fits), pressures to 7 MPa in 1 MPa steps up and down, 3 to 7 h per step; temperatures within 2 mK (ITS-90), pressure uncertainty 3e-5 p + 84 Pa. Densities from the reference equations of state: Tegeler et al. 1999 (Ar), Span et al. 2000 (N2), Schmidt and Wagner 1985 (O2), Setzmann and Wagner 1991 (CH4), Span and Wagner 1996 (CO2) (pp. 3-19).
Materials in structured entries: Ar, CH4, CO2, N2, O2
Dataset quantities: molar_refractivity
Contents: 9 datasets; 9 formulas.
Curation notes#
Identity checked against the first page (the pdf is an author copy titled ‘EightGasEpsValues’; journal pages 375-403 = pdf pages 1-29). Page numbers below are pdf pages.
WHAT A_eps IS. Molar polarizability wp = [(eps - 1)/(eps + 2)]/rho = A_eps(1 + b rho + c rho^2 + ...) (Eq. 5); the fits use Eq. (9): (eps - 1)/(eps + 2) = A_eps,273 rho (1 + b rho + c rho^2) + A_tau rho (T/273.16 K - 1) + q rho^2 (273.16 K/T - 1), ‘at most four coefficients’ per fit, all data weighted equally (p. 18). A_eps,273 is the zero-density molar polarizability at 273.16 K where A_tau is fitted, and a temperature-independent A_eps over 0-50 degrees C where it is not. It is the static (bridge-frequency) value: for Ar, N2 and O2 (no infrared-active vibration, no dipole) the electronic polarizability; for CH4 and CO2 it includes the static vibrational polarizability (hohm_2013 subtracts 0.23 au from CH4 and 2.18 au from CO2, i.e. 0.086 and 0.81 cm^3/mol). b, c, A_tau and q are dielectric virial and temperature coefficients whose uncertainties ‘from the equations of state are much larger than the indicated uncertainties’ (Table V caption); b is ‘determined via subtraction: b ~ B - A_eps + a_2/(3 A_eps)’ and its uncertainty ‘is dominated by the uncertainty of B’ (p. 20). They are recorded only in the formulas (no quantity holds b, a virial per unit A_eps; B_eps = A_eps b).
UNCERTAINTY (pp. 19-20, 25). Table V caption: ‘For the more satisfactory fits, the uncertainty of the last two digits of each coefficient is shown in parentheses. The uncertainty of A_eps,273 from the elastic properties of the capacitor is 1.1e-4 cm^3 mol^-1.’ No level is stated for the parentheses (fit uncertainties); stored as the sigma column, level ‘not stated’. The accuracy is larger: ‘the uncertainty of A_eps,273 is the quadrature sum of three terms: delta x A_eps,273, 1e-6 A_eps,273/(eps_max - 1), and 1.1e-4 cm^3 mol^-1’ with delta ~ 3e-5 from the pressure measurements (p. 19), and for N2 (p. 25) ‘The error from the fit must be augmented by the three contributions ... 1.3e-4 cm^3 mol^-1 from pressure measurements, 1.1e-4 from capacitance measurements, and 1.1e-4 from the deformation of the ring capacitor’. Computed here from that budget (not printed; eps_max from the 0 degrees C column of Table IV): the three terms add in quadrature to about 1.9e-4 (Ar, O2), 2.0e-4 (N2) and 2.4e-4 cm^3/mol (CH4); with the printed fit uncertainty, about 2.7e-4 (Ar), 2.7e-4 (N2, two-parameter fit), 2.1e-4 (O2, A_tau fit), 3.9e-4 cm^3/mol (CH4, four-parameter fit), i.e. 50-65 ppm. The p. 25 text gives N2 ‘A_eps = (4.3878 +- 0.0009) cm^3 mol^-1 where our uncertainty is from the two-parameter fit in Table V’, five times Table V’s (18) in the last digits: unexplained (0.0009 is also not the budget above). Temperature dependence: ‘the three parameters A_eps,273, A_tau and b in Eq. (9) are of interest to theory’ (p. 19); A_tau of O2 0.0065 cm^3/mol (Younglove’s -0.0059 inconsistent, p. 22), of N2 0.0017 (lowers sigma from 0.91 to 0.69), of CH4 ~6e-3 (four parameters) or ~11e-3 with a fifth parameter b_tau, bracketing Wong et al.’s calculated 8.4e-3 and below Bose et al.’s (1972) 17e-3 (p. 22).
PREFERRED FITS. N2: the text quotes the two-parameter value (p. 25). O2: the A_tau fit (Fig. 5d; ‘This is evidence that A_eps is temperature-dependent’, p. 21). CH4: the four-parameter fit (‘All four parameters are statistically significant’, p. 22). CO2: the four-parameter fit with q (Fig. 7b; ‘a temperature-dependent A_eps was much less significant than a rho^3 term’, p. 25). Every A_eps is recorded, use = check.
COMPARISONS (pp. 25-27). Ewing and Royal (2002), N2 at 300 K: A_eps = 4.3921 +- 0.0019, differing by 0.0043 +- 0.0021 cm^3/mol, ‘the known uncertainties are too small to explain the small inconsistency’. Straty and Goodwin’s CH4 wp lies 0.11-0.17 % below; Malbrunot et al. A_eps +- 0.002; Bose et al. (bose_1972) at 280, 323, 373 K; CO2’s q agrees with Bose and Cole’s B_eps decrease of 6.9 +- 1.3 cm^6/mol^2 from 29.4 to 49.7 degrees C (‘our value for the decrease is 6.5’). Oxygen agrees with Younglove within scatter (Fig. 9).
Not extracted (no quantity, or not a curated species): Tables I-IV, the raw 100(eps - 1) against p (kPa): He at 29.3 and 0.019 degrees C (Table I, the helium test), propane and ethane (Table II), and CH4, N2, CO2, Ar, O2 at 29.3 degrees C (Table III, whose Methane and Nitrogen columns are merged into shared cells in the CSV, with N2’s two extra points 3244.67/1.71409 and 2269.70/1.19627 merged into the last row) and 0.019 degrees C (Table IV). They are used below only to check the Eq. (9) formulas. The propane, ethane and CO2 three-parameter rows of Table V; the propane dipole term (Eq. 10, mu = 0.0848 D). Helium: no A_eps is fitted here (MB’s recommended helium values are used for the theory comparison, p. 9).
Reproductions of this paper: may_2008 (schmidt_moldover_2003_O2, its alpha_e 1.7461e-40 F m^2 = 3 eps0 A_eps/N_A of the O2 A_tau fit, 3.95875) and yang_2025 (schmidt_moldover_2003_N2, 4.3877(2)) cite it. May et al. (2008) also REFIT these O2 eps(p, T) data together with theirs (their Eq. 19): may_2008’s recommended O2 value is not independent of the O2 rows here (double-counting risk). hohm_2013 cites it for N2 (11.7379 au, the mean of the two N2 fits, 4.38765 cm^3/mol), O2 (with may_2008), CO2 (19.652 au = 7.34590) and CH4 (in a mean).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
schmidt_2003/A_eps_Ar#
{
"id": "A_eps_Ar",
"material": "Ar",
"file": "Ar/schmidt_2003__A_eps_Ar.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
}
}
Table V: A_eps,273 = 4.14203 (19) cm^3 mol^-1, the two-parameter fit (A_eps, b; Tegeler et al. EoS; 10^6 sigma = 0.98), independent of temperature over 0-50 degrees C. Static dielectric, electronic polarizability (argon). Parenthesised fit uncertainty as sigma (level not stated); the budget of the source notes gives about 2.7e-4 cm^3/mol in all.
schmidt_2003/A_eps_two_N2#
{
"id": "A_eps_two_N2",
"material": "N2",
"file": "N2/schmidt_2003__A_eps_two_N2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
}
}
Table V: A_eps,273 = 4.38782 (18) cm^3 mol^-1, two-parameter fit (A_eps, b; Span et al. EoS; 10^6 sigma = 0.91), independent of temperature over 0-50 degrees C: the value the text quotes (4.3878 +- 0.0009, p. 25; the +- there is five times the parentheses). Static dielectric, electronic. Budget about 2.7e-4 cm^3/mol (source notes).
schmidt_2003/A_eps_tau_N2#
{
"id": "A_eps_tau_N2",
"material": "N2",
"file": "N2/schmidt_2003__A_eps_tau_N2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"temperature_k": 273.16
}
}
Table V: A_eps,273 = 4.38748 (15) cm^3 mol^-1 at 273.16 K, three-parameter fit with A_tau = 0.00170 (30) (10^6 sigma = 0.69). Not independent of A_eps_two_N2 (the same data). Static dielectric, electronic.
schmidt_2003/A_eps_two_O2#
{
"id": "A_eps_two_O2",
"material": "O2",
"file": "O2/schmidt_2003__A_eps_two_O2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check"
}
Table V: A_eps,273 = 3.95945 cm^3 mol^-1, two-parameter fit (A_eps, b; Schmidt and Wagner EoS; 10^6 sigma = 1.86), no uncertainty printed: the fit the authors reject for O2 (the isotherm deviations have opposite slopes, p. 21). Static dielectric, electronic.
schmidt_2003/A_eps_tau_O2#
{
"id": "A_eps_tau_O2",
"material": "O2",
"file": "O2/schmidt_2003__A_eps_tau_O2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"temperature_k": 273.16
}
}
Table V: A_eps,273 = 3.95875 (09) cm^3 mol^-1 at 273.16 K, three-parameter fit with A_tau = 0.00648 (27) (10^6 sigma = 0.39): the preferred O2 fit (Fig. 5d). may_2008 refits these data with its own and reprints alpha_e = 1.7461e-40 F m^2 (= this value); its recommended 3.9576 is not independent of this one. Static dielectric, electronic. Budget about 2.1e-4 cm^3/mol (source notes).
schmidt_2003/A_eps_two_CH4#
{
"id": "A_eps_two_CH4",
"material": "CH4",
"file": "CH4/schmidt_2003__A_eps_two_CH4.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"parameters": {
"includes": "electronic + vibrational static polarizability"
}
}
Table V: A_eps,273 = 6.54787 cm^3 mol^-1, two-parameter fit (A_eps, b; Setzmann and Wagner EoS; 10^6 sigma = 2.95), no uncertainty printed (Fig. 6a; superseded by the four-parameter fit). Static dielectric: electronic plus vibrational.
schmidt_2003/A_eps_four_CH4#
{
"id": "A_eps_four_CH4",
"material": "CH4",
"file": "CH4/schmidt_2003__A_eps_four_CH4.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"temperature_k": 273.16,
"includes": "electronic + vibrational static polarizability"
}
}
Table V: A_eps,273 = 6.54467 (31) cm^3 mol^-1 at 273.16 K, four-parameter fit (b = 1.250 (34), c = -44.7 (68), A_tau = 0.00622 (36); 10^6 sigma = 0.86): the preferred CH4 fit (Fig. 6b). Static dielectric: electronic plus vibrational (the vibrational part is about 0.086 cm^3/mol, 1.3 %). Budget about 3.9e-4 cm^3/mol (source notes).
schmidt_2003/A_eps_three_CO2#
{
"id": "A_eps_three_CO2",
"material": "CO2",
"file": "CO2/schmidt_2003__A_eps_three_CO2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"parameters": {
"includes": "electronic + vibrational static polarizability"
}
}
Table V: A_eps,273 = 7.3797 cm^3 mol^-1, three-parameter fit (A_eps, b, A_tau = 0; Span and Wagner EoS; 10^6 sigma = 12.6), no uncertainty printed. The authors replace it by the four-parameter fit (quadrupole term q, p. 25); this row does not reproduce Tables III-IV (formula eq9_CO2_three). Static dielectric: electronic plus the large vibrational part of CO2.
schmidt_2003/A_eps_four_CO2#
{
"id": "A_eps_four_CO2",
"material": "CO2",
"file": "CO2/schmidt_2003__A_eps_four_CO2.csv",
"table": "tbl_d4ad17b1acdf",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "nm",
"use": "check",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"includes": "electronic + vibrational static polarizability"
}
}
Table V: A_eps,273 = 7.34590 (63) cm^3 mol^-1, four-parameter fit (b = 10.023 (80), c = -557. (20), q = 114.21 (61); 10^6 sigma = 1.3), independent of temperature (no A_tau): the preferred CO2 fit (Fig. 7b). The CO2 data used the older bath and are less precise; for CO2 the capacitance term dominates the A_eps budget (p. 19). Static dielectric: electronic plus vibrational (hohm_2013 subtracts 2.18 au = 0.81 cm^3/mol, 11 %). hohm_2013 reprints it as 19.652 +- 0.002 au.
Formulas#
schmidt_2003/eq9_Ar#
{
"id": "eq9_Ar",
"material": "Ar",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "(eps - 1)/(eps + 2) = A_eps,273 rho (1 + b rho + c rho^2) + A_tau rho (T/273.16 K - 1) + q rho^2 (273.16 K/T - 1); Ar [13]: A_eps,273 = 4.14203 (19), b = 0.281 (15), 10^6 sigma = 0.98",
"variable": "rho: molar density in mol/cm^3 (from the Tegeler et al. 1999 equation of state); T: temperature in K; A_eps,273, b in cm^3/mol; eps: static relative permittivity",
"range": "0-50 degrees C, 0-7 MPa (the fitted isotherms, with MB's 50 degrees C data)",
"coefficients": {
"A_eps_273": "4.14203",
"b": "0.281"
},
"check": "With CoolProp's Tegeler equation of state (the paper's Ref. 13), reproduces the 26 non-zero points of Tables III (29.3 C) and IV (0.019 C) to 1.39 ppm rms in eps (mean -0.88 ppm), against the printed fit standard deviation 0.98 ppm over all isotherms. Checked 2026-09-26."
}
Two-parameter fit; c, A_tau, q zero.
schmidt_2003/eq9_N2_two#
{
"id": "eq9_N2_two",
"material": "N2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); N2 [14]: A_eps,273 = 4.38782 (18), b = 0.399 (14), 10^6 sigma = 0.91",
"variable": "rho: molar density in mol/cm^3 (Span et al. 2000 equation of state); T in K; A_eps,273, b in cm^3/mol",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "4.38782",
"b": "0.399"
},
"check": "With CoolProp's Span et al. equation of state (Ref. 14), reproduces the 28 non-zero points of Tables III-IV to 1.31 ppm rms (mean -0.69 ppm); printed sigma 0.91 ppm. Checked 2026-09-26."
}
Two-parameter fit.
schmidt_2003/eq9_N2_tau#
{
"id": "eq9_N2_tau",
"material": "N2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); N2 [14]: A_eps,273 = 4.38748 (15), b = 0.417 (11), A_tau = 0.00170 (30), 10^6 sigma = 0.69",
"variable": "rho: molar density in mol/cm^3 (Span et al. 2000); T in K; A_eps,273, b, A_tau in cm^3/mol",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "4.38748",
"b": "0.417",
"A_tau": "0.00170"
},
"check": "Reproduces the 28 non-zero points of Tables III-IV to 0.80 ppm rms (mean -0.25 ppm); printed sigma 0.69 ppm. Checked 2026-09-26."
}
A_tau lowers sigma from 0.91 to 0.69 (p. 21).
schmidt_2003/eq9_O2_two#
{
"id": "eq9_O2_two",
"material": "O2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); O2 [15]: A_eps,273 = 3.95945, b = -0.113, 10^6 sigma = 1.86",
"variable": "rho: molar density in mol/cm^3 (Schmidt and Wagner 1985); T in K; A_eps,273, b in cm^3/mol",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "3.95945",
"b": "-0.113"
},
"check": "Reproduces the 26 non-zero points of Tables III-IV to 2.00 ppm rms (mean -0.46 ppm); printed sigma 1.86 ppm. Checked 2026-09-26."
}
Rejected by the authors in favour of eq9_O2_tau (Fig. 5c-d).
schmidt_2003/eq9_O2_tau#
{
"id": "eq9_O2_tau",
"material": "O2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); O2 [15]: A_eps,273 = 3.95875 (09), b = -0.077 (07), A_tau = 0.00648 (27), 10^6 sigma = 0.39",
"variable": "rho: molar density in mol/cm^3 (Schmidt and Wagner 1985); T in K; A_eps,273, b, A_tau in cm^3/mol",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "3.95875",
"b": "-0.077",
"A_tau": "0.00648"
},
"check": "Reproduces the 26 non-zero points of Tables III-IV to 0.49 ppm rms (mean -0.10 ppm); printed sigma 0.39 ppm. Checked 2026-09-26."
}
The preferred O2 fit. may_2008 refits these data with its own (its Eq. 19: A_eps,273 = 3.95760, A_tau = 0.0037).
schmidt_2003/eq9_CH4_two#
{
"id": "eq9_CH4_two",
"material": "CH4",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); CH4 [19]: A_eps,273 = 6.54787, b = 0.981, 10^6 sigma = 2.95",
"variable": "rho: molar density in mol/cm^3 (Setzmann and Wagner 1991); T in K; A_eps,273, b in cm^3/mol",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "6.54787",
"b": "0.981"
},
"check": "Reproduces the 26 non-zero points of Tables III-IV to 5.12 ppm rms (mean -3.93 ppm); printed sigma 2.95 ppm (Fig. 6a shows structured residuals). Checked 2026-09-26."
}
Superseded by eq9_CH4_four.
schmidt_2003/eq9_CH4_four#
{
"id": "eq9_CH4_four",
"material": "CH4",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); CH4 [19]: A_eps,273 = 6.54467 (31), b = 1.250 (34), c = -44.7 (68), A_tau = 0.00622 (36), 10^6 sigma = 0.86",
"variable": "rho: molar density in mol/cm^3 (Setzmann and Wagner 1991); T in K; A_eps,273, b, A_tau in cm^3/mol; c in cm^6/mol^2",
"range": "0-50 degrees C, 0-7 MPa",
"coefficients": {
"A_eps_273": "6.54467",
"b": "1.250",
"c": "-44.7",
"A_tau": "0.00622"
},
"check": "Reproduces the 26 non-zero points of Tables III-IV to 1.86 ppm rms (mean -0.53 ppm); printed sigma 0.86 ppm over all isotherms. Checked 2026-09-26."
}
The preferred CH4 fit (Fig. 6b). Adding a fifth parameter b_tau gives A_tau ~ 11e-3 (p. 22; not tabulated).
schmidt_2003/eq9_CO2_three#
{
"id": "eq9_CO2_three",
"material": "CO2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); CO2 [26]: A_eps,273 = 7.3797, b = 6.230, A_tau = 0, 10^6 sigma = 12.6",
"variable": "rho: molar density in mol/cm^3 (Span and Wagner 1996); T in K; A_eps,273, b, A_tau in cm^3/mol",
"range": "0-50 degrees C (CO2: 0.90 < T/T_c < 1.06, rho/rho_c < 0.26), to about 5 MPa",
"coefficients": {
"A_eps_273": "7.3797",
"b": "6.230",
"A_tau": "0"
},
"check": "DOES NOT reproduce Tables III-IV: residuals -20 to -36 ppm (and +34 at the highest density) on the 0.019 C isotherm and -27 to -175 ppm, growing with density, on the 29.3 C isotherm (73 ppm rms), against the printed sigma 12.6 ppm. The fitted data include isotherms not tabulated (23, 40 C and MB's 50 C), but no single misprint explains the 29.3 C trend; unresolved (checked 2026-09-26). The four-parameter fit (eq9_CO2_four) reproduces the same points to 1.6 ppm."
}
Rejected by the authors (‘a factor of 5 larger’ sigma than ethane’s, p. 25).
schmidt_2003/eq9_CO2_four#
{
"id": "eq9_CO2_four",
"material": "CO2",
"equation": "Eq. (9), p. 18; Table V, p. 20",
"printed": "Eq. (9); CO2 [26]: A_eps,273 = 7.34590 (63), b = 10.023 (80), c = -557. (20), q = 114.21 (61), 10^6 sigma = 1.3",
"variable": "rho: molar density in mol/cm^3 (Span and Wagner 1996); T in K; A_eps,273, b in cm^3/mol; c, q in cm^6/mol^2",
"range": "0-50 degrees C (0.90 < T/T_c < 1.06, rho/rho_c < 0.26)",
"coefficients": {
"A_eps_273": "7.34590",
"b": "10.023",
"c": "-557.",
"q": "114.21"
},
"check": "Reproduces the 22 non-zero points of Tables III-IV to 1.61 ppm rms (mean -0.13 ppm); printed sigma 1.3 ppm. Its q gives the decrease of B_eps = A_eps b + q (273.16/T - 1) from 29.4 to 49.7 C as 6.48 cm^6/mol^2, the text's 'our value for the decrease is 6.5' (p. 25). Checked 2026-09-26."
}
The preferred CO2 fit (Fig. 7b); q allows for the quadrupole (1/T) term of the dielectric second virial.
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.