buckingham_1969#
A. D. Buckingham and B. J. Orr, “Kerr effect in methane and its four fluorinated derivatives”, Trans. Faraday Soc. 65, 673 (1969)
Source record · Catalogue · Review register
DOI: 10.1039/tf9696500673
Source kind: measurement
Recorded technique: Absolute dc Kerr effect (electric birefringence) at 632.8 nm (He-Ne laser) with the apparatus of Boyle et al. 1966, Buckingham & Dunmur 1968 and Buckingham & Orr 1968 (phase-sensitive detection; thermostat -30 to +60 C); pressures to 2 bar on a glass line with a mercury manometer, to 100 bar on a steel line with a calibrated Budenberg gauge. mK0 = (2/27) V (n_par - n_perp) F^-2 per measurement (Eq. 6), fitted to mK0 = A_K + [B_K + A_K(2 A_eps + A_R/2)] V^-1 (Eq. 7), molar volumes from literature virial coefficients (CH4: Schamp et al. 1958). CH4 (commercial, purity better than 98 %, ‘the only significant impurity being air’) at 249.7, 273.6 and 303.7 K, 8-30 bar, 18-20 measurements each (pp. 673-675).
Materials in structured entries: CH4
Dataset quantities: hyperpolarizability, kerr_virial_coefficient, molar_kerr_constant
Contents: 3 datasets; 0 formulas.
Curation notes#
Pages are the journal’s (673-681; p. = pdf page + 672). CH4 ONLY is recorded; the paper also measures CF4 (gamma = 0.093 +- 0.005 x 10^-60 C^4 m^4 J^-3; A_K 0.078, B_K 0.422 at 288.8 K), CH3F, CH2F2 and CHF3 (A_K, B_K against temperature; Table 3’s beta, (alpha_33 - alpha), dipole moments, polarizabilities; Table 4’s term-by-term A_K at 300 K), all out of scope and not transcribed.
DEFINITIONS (pp. 673-674). mK = 6 n V (n_par - n_perp)[(n^2 + 2)(eps + 2) F]^-2 (Eq. 1); mK = A_K + B_K V^-1 (Eq. 2); A_K = (N/(81 eps0))[gamma + (kT)^-1((2/3) mu beta + (9/5) alpha^(0) alpha kappa^2) + (3/10)(kT)^-2 mu^2 (alpha_33 - alpha)] (Eq. 3, S.I.), with gamma = (1/10)(3 gamma_xi eta,xi eta - gamma_xi xi,eta eta) (Eq. 5): Buckingham’s dc Kerr gamma_K in the Taylor-series convention. ‘For the tetrahedral molecules methane and tetrafluoromethane only the term involving gamma in eqn. (3) is non-zero, so that A_K should be temperature-independent’ (p. 674); A_K = N gamma/81 eps0 (Eq. 8). The S.I. units of Table 1 are printed ‘C^2 m^5 J^-2’ for A_K and ‘C^2 m^8 J^-2’ for B_K (per mole and per mole squared implied: N is Avogadro’s number, V the molar volume); the extraction reads the A_K header as ‘C^2m^3J^-2’, the image shows m^5. Table 6 (appendix): 1 S.I. unit of gamma = 8.0776 x 10^24 e.s.u.; of mK, A_K 0.89876 x 10^15 e.s.u.; of B_K 0.89876 x 10^21 e.s.u.
RESULT (p. 677): ‘Measurements of A_K for CH4 (table 1) show no significant trend with temperature, which is consistent with eqn. (8). Results in table 1 yield: 10^60 gamma(CH4) = 0.180 +- 0.009 C^4 m^4 J^-3’. Checked (2026-09-26): 81 eps0/N_A x mean A_K (0.1507 x 10^-27) = 0.179 x 10^-60; the +-0.009 is the 5 % absolute accuracy. In au (6.235377e-65): 2887 +- 144 (shelton_1994 Table XII: 2887 +- 140).
ACCURACY (pp. 675-676): ‘The estimated precision of A_K is +-2 %, but the absolute accuracy is +-5 % as a result of calibration uncertainties; the precision of B_K for CH4, CF4 and CH2F2 is +-10 %’.
TABLE 2 (p. 676), mK of CH4 at 298 K and 105-425 bar: Kuss & Stuart (Physik. Z. 42, 95 (1941)) 0.24-0.27 x 10^-27 against this work’s linear extrapolation 0.27-0.53 x 10^-27 (‘The uncertainties in the extrapolations vary from +-5 % at 105 bar to +-8 % at 425 bar’); ‘The deviation at high pressures ... might be due to the effect of a negative third Kerr virial coefficient’. No quantity holds a finite-density molar Kerr constant: notes only. TABLE 5 (p. 680): B_K(obs.) of CH4 0.30 +- 0.03, 0.28 +- 0.03, 0.24 +- 0.02 x 10^-31 at 250, 274, 304 K (Table 1’s values rounded, with the 10 %) against B_K(calc.) 0.34, 0.31, 0.27 from the pair-anisotropy theory of Buckingham & Dunmur with alpha = 2.90, alpha^(0) = 2.88 x 10^-40 C^2 m^2 J^-1 and Lennard-Jones eps/k = 148.2 K, sigma = 0.382 nm (Hirschfelder, Curtiss & Bird): ‘The agreement is good for CH4’ (p. 680).
Reproductions elsewhere: shelton_1986_ch4/table2_dc_kerr (180 +- 9 x 10^-63 C^4 m^4 J^-3, digit-identical), shelton_1994/table12_CH4_dc_kerr row ‘ref 28’ (2887 +- 140 au). Not edited here: lundeen_1983, ward_1984 cite this paper’s CH4 value too. The library’s validation findings are informational (figure grouping, page headers).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
buckingham_1969/table1_A_K_CH4#
{
"id": "table1_A_K_CH4",
"material": "CH4",
"file": "CH4/buckingham_1969__table1_A_K_CH4.csv",
"table": "tbl_d2bf39485ac8",
"quantity": "molar_kerr_constant",
"unit": "C2 m5 J-2",
"scale": 1e-27,
"abscissa": "temperature",
"abscissa_unit": "K",
"use": "check",
"uncertainty": {
"relative": 0.05,
"level": "not stated"
},
"parameters": {
"wavelength_nm": 632.8
}
}
Table 1 (p. 675), METHANE: A_K at 249.7, 273.6 and 303.7 K (8-30 bar, 18-20 measurements each), 632.8 nm, in S.I. units as printed (C^2 m^5 J^-2, per mole). No orientation term for CH4: A_K = N gamma/81 eps0, so text_gamma_CH4 is these values averaged (fit that one, not both). Uncertainty: the ‘absolute accuracy is +-5 % as a result of calibration uncertainties’ (the precision is +-2 %); level not stated.
buckingham_1969/table1_B_K_CH4#
{
"id": "table1_B_K_CH4",
"material": "CH4",
"file": "CH4/buckingham_1969__table1_B_K_CH4.csv",
"table": "tbl_d2bf39485ac8",
"quantity": "kerr_virial_coefficient",
"unit": "C2 m8 J-2",
"scale": 1e-31,
"abscissa": "temperature",
"abscissa_unit": "K",
"use": "check",
"uncertainty": {
"relative": 0.1,
"level": "not stated"
},
"parameters": {
"wavelength_nm": 632.8,
"order": 2
}
}
Table 1 (p. 675), METHANE: the second Kerr virial coefficient B_K (Eq. 2) at 249.7, 273.6 and 303.7 K, in S.I. units as printed (C^2 m^8 J^-2, per mole squared). ‘the precision of B_K for CH4, CF4 and CH2F2 is +-10 %’ (p. 676; Table 5 prints these as 0.30 +- 0.03, 0.28 +- 0.03, 0.24 +- 0.02).
buckingham_1969/text_gamma_CH4#
{
"id": "text_gamma_CH4",
"material": "CH4",
"table": "text",
"quantity": "hyperpolarizability",
"unit": "SI",
"scale": 1e-60,
"abscissa_unit": "nm",
"wavelength_medium": "standard_air",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"process": "dc_kerr",
"convention": "T",
"part": "total",
"component": "K"
}
}
1 inline points in the source record.
p. 677: ‘10^60 gamma(CH4) = 0.180 +- 0.009 C^4 m^4 J^-3’ (2887 +- 144 au), the dc Kerr gamma_K of CH4 at 632.8 nm from the temperature-independent A_K of Table 1 by Eq. (8). A tetrahedral molecule has no orientation term, so gamma is the total dc Kerr response (electronic plus vibrational). The error is the 5 % absolute accuracy (calibration); level not stated. shelton_1986_ch4 finds it about 10 % above the ESHG-predicted dc Kerr value.
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.