st_arnaud_1976#
J. M. St-Arnaud and T. K. Bose, “Direct determination of the second refractivity virial coefficient of CH4”, J. Chem. Phys. 65, 4854 (1976)
Source record · Catalogue · Review register
DOI: 10.1063/1.432959
Source kind: measurement
Recorded technique: Direct (differential) determination of the second refractivity virial coefficient after Buckingham et al.: two nearly equal stainless-steel optical cells (path lengths 6.3238 and 6.3030 cm, 1.75 cm quartz windows) joined by a valve; the gas in one cell is expanded into the other (density nearly halved) and the change of the summed optical path is measured with a Hewlett-Packard 5525A heterodyne He-Ne laser interferometer (6328 A), Eq. (8); seven expansions from 120-180 atm. A_R and B_P from the absolute refractive index against pressure below 12 atm (Eq. 9; quartz Bourdon gauge calibrated against a pressure standard). Bath at 29.72 C (+-0.01 C). Matheson methane, 99.97 % minimum (pp. 4854-4855).
Materials in structured entries: CH4
Dataset quantities: molar_refractivity, refractivity_virial_coefficient
Contents: 7 datasets; 0 formulas.
Curation notes#
Identity: VALIDATED_WITH_WARNINGS in the library (a caption warning only); first page checked (pdf page 2: J. Chem. Phys. 65, 4854 (1976), received 23 June 1976; pdf page 1 is the publisher’s cover). Page numbers are journal pages (pdf page + 4852).
DEFINITIONS (Eqs. 1-5, p. 4854): R_m = (n^2 - 1)/(n^2 + 2)/d = A_R + B_R d + C_R d^2, d the molar density; (n - 1)/d = A_n + B_n d + ...; A_R = 2 A_n/3, B_R = 2 B_n/3 - A_n^2/9. A_R is the package’s molar_refractivity and B_R its refractivity_virial_coefficient.
TEMPERATURE: ‘measurements were made for methane at 29.72 C’ (p. 4855), i.e. 302.87 K; the table prints 302 K; the theory at 302.7 K (p. 4856). The B_R dataset takes 302.87 K.
ACCURACY: ‘Our estimated error for A_R and B_R is one standard deviation for a least squares fit’ (p. 4856); no C_R was detected up to 180 atm; the window-distortion correction to B_R, -0.08 cm^6/mol^2, was applied; path-length and volume changes with pressure were neglected.
A_R IS LOW: 6.533 +- 0.002 cm^3/mol at 6328 A is 0.62 % below the curated CH4 dispersion at 632.99 nm (fit/CH4 default model, 6.574 cm^3/mol, computed 2026-09-25), 1.0 % below Buckingham and Graham’s 6.600 at the same wavelength, and the authors note it ‘agrees well with the value of A_eps obtained from the dielectric measurements’ (p. 4855), a static value that should lie about 2 % lower. Olson’s 6.614 at 5462 A is 0.07 % below the curated value there (6.618). The A_R dataset is therefore excluded; B_R, measured differentially and independent of the absolute pressure scale, is kept.
Not extracted: B_P = -42.0 +- 0.4 cm^3/mol (this work) and -44.0 +- 3.0 (Olson), density virial coefficients (no quantity); the Lennard-Jones parameters of the theory row (epsilon/k = 148.6 K, sigma = 3.758 A, from viscosity; footnote a).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
st_arnaud_1976/B_R_this_work#
{
"id": "B_R_this_work",
"material": "CH4",
"file": "CH4/st_arnaud_1976__B_R_this_work_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "refractivity_virial_coefficient",
"unit": "cm6/mol2",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "1 sigma"
},
"parameters": {
"temperature_k": 302.87
}
}
Table 1 ‘Our work’: B_R = 6.60 +- 0.38 cm^6/mol^2 at 6328 A (He-Ne, air wavelength) and 29.72 C, the mean of seven direct (expansion) measurements from 120-180 atm; one standard deviation. The paper’s rounded 302 K in the table.
st_arnaud_1976/A_R_this_work#
{
"id": "A_R_this_work",
"material": "CH4",
"file": "CH4/st_arnaud_1976__A_R_this_work_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "excluded",
"uncertainty": {
"column": true,
"level": "1 sigma"
}
}
Table 1 ‘Our work’: A_R = 6.533 +- 0.002 cm^3/mol at 6328 A, 302 K, from the absolute refractive index below 12 atm (Eq. 9). EXCLUDED: 0.62 % below the curated CH4 dispersion at 632.99 nm and 1.0 % below Buckingham and Graham at the same wavelength, far beyond the stated one-sigma 0.002 (source notes).
st_arnaud_1976/A_R_buckingham_graham_1974#
{
"id": "A_R_buckingham_graham_1974",
"material": "CH4",
"file": "CH4/st_arnaud_1976__A_R_buckingham_graham_1974_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "reproduced",
"reproduced_from": [
"buckingham_1974"
],
"uncertainty": {
"column": true,
"level": "not stated"
}
}
Table 1 ‘Buckingham and Graham’, 299 K, 6328 A: A_R = 6.600 +- 0.002 cm^3/mol (level not stated).
st_arnaud_1976/B_R_buckingham_graham_1974#
{
"id": "B_R_buckingham_graham_1974",
"material": "CH4",
"file": "CH4/st_arnaud_1976__B_R_buckingham_graham_1974_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "refractivity_virial_coefficient",
"unit": "cm6/mol2",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "reproduced",
"reproduced_from": [
"buckingham_1974"
],
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"temperature_k": 299.0
}
}
Table 1 ‘Buckingham and Graham’, 299 K, 6328 A: B_R = 7.15 +- 0.35 cm^6/mol^2, ‘slightly higher than ours’ (p. 4855).
st_arnaud_1976/A_R_olson_1975#
{
"id": "A_R_olson_1975",
"material": "CH4",
"file": "CH4/st_arnaud_1976__A_R_olson_1975_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "molar_refractivity",
"unit": "cm3/mol",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "reproduced",
"reproduced_from": [
"J. D. Olson, J. Chem. Phys. 63, 474 (1975)"
],
"uncertainty": {
"column": true,
"level": "not stated"
}
}
Table 1 ‘Olson’, 300 K, 5462 A: A_R = 6.614 +- 0.002 cm^3/mol (Ref. 9). The original is not in the library.
st_arnaud_1976/B_R_olson_1975#
{
"id": "B_R_olson_1975",
"material": "CH4",
"file": "CH4/st_arnaud_1976__B_R_olson_1975_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "refractivity_virial_coefficient",
"unit": "cm6/mol2",
"abscissa_unit": "angstrom",
"wavelength_medium": "standard_air",
"use": "reproduced",
"reproduced_from": [
"J. D. Olson, J. Chem. Phys. 63, 474 (1975)"
],
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"temperature_k": 300.0
}
}
Table 1 ‘Olson’, 300 K, 5462 A: B_R = 5.5 +- 1.0 cm^6/mol^2, from refractive index against density (not a direct measurement). The original is not in the library.
st_arnaud_1976/B_R_kirkwood_theory#
{
"id": "B_R_kirkwood_theory",
"material": "CH4",
"file": "CH4/st_arnaud_1976__B_R_kirkwood_theory_CH4.csv",
"table": "tbl_e86bfa5ea90a",
"quantity": "refractivity_virial_coefficient",
"unit": "cm6/mol2",
"abscissa_unit": "angstrom",
"wavelength_medium": "vacuum",
"use": "check",
"parameters": {
"temperature_k": 302.7
}
}
Table 1 ‘Kirkwood (theory)’, 302 K: B_R = 6.11 cm^6/mol^2 (text: 6.1 at 302.7 K, p. 4856), the classical dipole-induced-dipole term B_DID = (2/3)(4 pi N_0 alpha)^2 alpha <R^-6> with a Lennard-Jones potential from viscosity (footnote a: epsilon/k = 148.6 K, sigma = 3.758 A). No wavelength is printed (filed at ‘inf’; the alpha used is not stated). The authors’ calculation, 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 review register for the checks and decisions.