dalgarno_1960#
A. Dalgarno and A. E. Kingston, Proc. R. Soc. London A 259, 424 (1960)
Source record · Catalogue · Review register
Source kind: fit
Recorded technique: Semi-empirical: n^2 - 1 expanded in the Cauchy sums S(-2), S(-4), S(-6), ... (Eq. 2); S(-2) and S(-4) estimated from long-wavelength refractive indices of Cuthbertson and Cuthbertson (1911, 1932) and Korff and Breit (1932), the higher sums from the interpolation formula S(k) = {a + b/(2.5 - k) + c/(2.5 - k)^2}^k S(0) (Eq. 18) with a the first excitation energy (pp. 424-429).
Materials in structured entries: Ar, He, Kr, Ne, Xe
Dataset quantities: cauchy_moment, polarizability
Contents: 15 datasets; 5 formulas.
Curation notes#
Not independent data: the polarizabilities and dispersion formulas are derived from Cuthbertson and Cuthbertson’s refractivities (cuthbertson_1910, cuthbertson_1932) and Korff and Breit’s (1932) compilation. Energies are in rydbergs, so S(k) is in Ry^k: the datasets convert with scale 2^-k. Eq. (1) gives n^2 - 1 ‘at atmospheric pressure’ with the prefactor 2.00e-4 (4 pi N a0^3 with Loschmidt’s number, i.e. 0 degrees C, 1 atm, ideal gas); the Cuthbertsons’ data are for 0 degrees C, 760 mm.
Table 1’s helium ‘exact’ S(k) are sums over Dalgarno and Stewart’s (1960) oscillator strengths (S(-1) from Pekeris), the other column Eq. (18); atomic hydrogen’s are not extracted (H is not a curated species). Table 3 (expectation values of (sum r_i)^2) and the Verdet-constant formulas (in microminutes, from Eq. 5) are not extracted: they are not dispersion data (the Verdet formulas are consequences of the n^2 - 1 series). The Kr n^2 - 1 formula has no element label in the library’s Markdown; it is the fourth of the five (He, Ne, Ar, Kr, Xe order).
Consistency (checked 2026-09-24): the static limits of the n^2 - 1 formulas, converted with Lorentz-Lorenz at Loschmidt’s number and the paper’s a0^3 = 1.482e-25 cm^3, give He 1.384, Ar 11.084, Kr 16.737, Xe 27.29 (Table 2: 1.384, 11.080, 16.734, 27.292) but Ne 2.668 against Table 2’s 2.663 (0.2 %); not resolved. The He formula gives n - 1 = 3.4897e-5 at 5462 A, Cuthbertson and Cuthbertson’s 3.489e-5.
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
dalgarno_1960/s_exact_0#
{
"id": "s_exact_0",
"material": "He",
"file": "He/dalgarno_1960__s_exact_0.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 1,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(0) ‘exact’ (from Dalgarno and Stewart’s oscillator strengths; S(-1) from Pekeris), in Ry^0; scale 2^(0) gives atomic units.
dalgarno_1960/s_eq18_0#
{
"id": "s_eq18_0",
"material": "He",
"file": "He/dalgarno_1960__s_eq18_0.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 1,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(0) from the interpolation formula Eq. (18), in Ry^0; scale 2^(0) gives atomic units.
dalgarno_1960/s_exact_m1#
{
"id": "s_exact_m1",
"material": "He",
"file": "He/dalgarno_1960__s_exact_m1.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 2,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-1) ‘exact’ (from Dalgarno and Stewart’s oscillator strengths; S(-1) from Pekeris), in Ry^-1; scale 2^(1) gives atomic units.
dalgarno_1960/s_eq18_m1#
{
"id": "s_eq18_m1",
"material": "He",
"file": "He/dalgarno_1960__s_eq18_m1.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 2,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-1) from the interpolation formula Eq. (18), in Ry^-1; scale 2^(1) gives atomic units.
dalgarno_1960/s_exact_m2#
{
"id": "s_exact_m2",
"material": "He",
"file": "He/dalgarno_1960__s_exact_m2.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 4,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-2) ‘exact’ (from Dalgarno and Stewart’s oscillator strengths; S(-1) from Pekeris), in Ry^-2; scale 2^(2) gives atomic units.
dalgarno_1960/s_eq18_m2#
{
"id": "s_eq18_m2",
"material": "He",
"file": "He/dalgarno_1960__s_eq18_m2.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 4,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-2) from the interpolation formula Eq. (18), in Ry^-2; scale 2^(2) gives atomic units.
dalgarno_1960/s_exact_m4#
{
"id": "s_exact_m4",
"material": "He",
"file": "He/dalgarno_1960__s_exact_m4.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 16,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-4) ‘exact’ (from Dalgarno and Stewart’s oscillator strengths; S(-1) from Pekeris), in Ry^-4; scale 2^(4) gives atomic units.
dalgarno_1960/s_eq18_m4#
{
"id": "s_eq18_m4",
"material": "He",
"file": "He/dalgarno_1960__s_eq18_m4.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 16,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-4) from the interpolation formula Eq. (18), in Ry^-4; scale 2^(4) gives atomic units.
dalgarno_1960/s_exact_m6#
{
"id": "s_exact_m6",
"material": "He",
"file": "He/dalgarno_1960__s_exact_m6.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 64,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-6) ‘exact’ (from Dalgarno and Stewart’s oscillator strengths; S(-1) from Pekeris), in Ry^-6; scale 2^(6) gives atomic units.
dalgarno_1960/s_eq18_m6#
{
"id": "s_eq18_m6",
"material": "He",
"file": "He/dalgarno_1960__s_eq18_m6.csv",
"table": "tbl_61824749ae46",
"quantity": "cauchy_moment",
"unit": "au",
"scale": 64,
"abscissa": "order",
"abscissa_unit": "1",
"use": "check"
}
Table 1, helium S(-6) from the interpolation formula Eq. (18), in Ry^-6; scale 2^(6) gives atomic units.
dalgarno_1960/alpha_He#
{
"id": "alpha_He",
"material": "He",
"file": "He/dalgarno_1960__alpha_He.csv",
"table": "tbl_07f29f0464dd",
"quantity": "polarizability",
"unit": "au",
"abscissa_unit": "angstrom",
"use": "check"
}
Table 2, static polarizability in a0^3 (the paper’s a0^3 = 1.482e-25 cm^3), derived from the Cuthbertsons’ refractivities through the formulas below; not independent of those data.
dalgarno_1960/alpha_Ne#
{
"id": "alpha_Ne",
"material": "Ne",
"file": "Ne/dalgarno_1960__alpha_Ne.csv",
"table": "tbl_07f29f0464dd",
"quantity": "polarizability",
"unit": "au",
"abscissa_unit": "angstrom",
"use": "check"
}
Table 2, static polarizability in a0^3 (the paper’s a0^3 = 1.482e-25 cm^3), derived from the Cuthbertsons’ refractivities through the formulas below; not independent of those data.
dalgarno_1960/alpha_Ar#
{
"id": "alpha_Ar",
"material": "Ar",
"file": "Ar/dalgarno_1960__alpha_Ar.csv",
"table": "tbl_07f29f0464dd",
"quantity": "polarizability",
"unit": "au",
"abscissa_unit": "angstrom",
"use": "check"
}
Table 2, static polarizability in a0^3 (the paper’s a0^3 = 1.482e-25 cm^3), derived from the Cuthbertsons’ refractivities through the formulas below; not independent of those data.
dalgarno_1960/alpha_Kr#
{
"id": "alpha_Kr",
"material": "Kr",
"file": "Kr/dalgarno_1960__alpha_Kr.csv",
"table": "tbl_07f29f0464dd",
"quantity": "polarizability",
"unit": "au",
"abscissa_unit": "angstrom",
"use": "check"
}
Table 2, static polarizability in a0^3 (the paper’s a0^3 = 1.482e-25 cm^3), derived from the Cuthbertsons’ refractivities through the formulas below; not independent of those data.
dalgarno_1960/alpha_Xe#
{
"id": "alpha_Xe",
"material": "Xe",
"file": "Xe/dalgarno_1960__alpha_Xe.csv",
"table": "tbl_07f29f0464dd",
"quantity": "polarizability",
"unit": "au",
"abscissa_unit": "angstrom",
"use": "check"
}
Table 2, static polarizability in a0^3 (the paper’s a0^3 = 1.482e-25 cm^3), derived from the Cuthbertsons’ refractivities through the formulas below; not independent of those data.
Formulas#
dalgarno_1960/n2_minus_1_He#
{
"id": "n2_minus_1_He",
"material": "He",
"equation": "unnumbered, p. 428",
"printed": "n^2 - 1 = 6.927 x 10^-5 (1 + 2.24 x 10^5/lambda^2 + 5.94 x 10^10/lambda^4 + 1.72 x 10^16/lambda^6 + ...)",
"variable": "lambda: wavelength in Angstrom (medium not stated; the fitted data mix the 1910 air and the 1932 vacuum wavelengths, a difference of 3e-4 in lambda)",
"state": "1atm_0C",
"density": "ideal",
"range": "the Cuthbertsons' visible and near-UV data; 'values in harmony with the available experimental data at all wavelengths' (p. 428)",
"coefficients": {
"a": "6.927e-5",
"c2": "2.24e5",
"c4": "5.94e10",
"c6": "1.72e16"
},
"check": "Static limit 1.3845 a.u. (Table 2: 1.384); n - 1 = 3.4897e-5 at 5462 A (Cuthbertson 1932: 3.489e-5). Lorentz-Lorenz at Loschmidt's number with a0^3 = 1.482e-25 cm^3. Checked 2026-09-24."
}
A Cauchy series in S(-2k); the paper’s form of n^2 - 1 (Eq. 2), not n - 1. Truncated where printed (’...’).
dalgarno_1960/n2_minus_1_Ne#
{
"id": "n2_minus_1_Ne",
"material": "Ne",
"equation": "unnumbered, p. 428",
"printed": "n^2 - 1 = 1.335 x 10^-4 (1 + 2.24 x 10^5/lambda^2 + 8.09 x 10^10/lambda^4 + 3.56 x 10^16/lambda^6 + ...)",
"variable": "lambda: wavelength in Angstrom (medium not stated; the fitted data mix the 1910 air and the 1932 vacuum wavelengths, a difference of 3e-4 in lambda)",
"state": "1atm_0C",
"density": "ideal",
"range": "the Cuthbertsons' visible and near-UV data; 'values in harmony with the available experimental data at all wavelengths' (p. 428)",
"coefficients": {
"a": "1.335e-4",
"c2": "2.24e5",
"c4": "8.09e10",
"c6": "3.56e16"
},
"check": "Static limit 2.668 a.u. against Table 2's 2.663 (0.2 %, unexplained); the leading term equals twice the Cuthbertsons' 1932 C/n0^2 = 6.673e-5. Lorentz-Lorenz at Loschmidt's number with a0^3 = 1.482e-25 cm^3. Checked 2026-09-24."
}
A Cauchy series in S(-2k); the paper’s form of n^2 - 1 (Eq. 2), not n - 1. Truncated where printed (’...’).
dalgarno_1960/n2_minus_1_Ar#
{
"id": "n2_minus_1_Ar",
"material": "Ar",
"equation": "unnumbered, p. 428",
"printed": "n^2 - 1 = 5.547 x 10^-4 (1 + 5.15 x 10^5/lambda^2 + 4.19 x 10^11/lambda^4 + 4.09 x 10^17/lambda^6 + 4.32 x 10^23/lambda^8 + ...)",
"variable": "lambda: wavelength in Angstrom (medium not stated; the fitted data mix the 1910 air and the 1932 vacuum wavelengths, a difference of 3e-4 in lambda)",
"state": "1atm_0C",
"density": "ideal",
"range": "the Cuthbertsons' visible and near-UV data; 'values in harmony with the available experimental data at all wavelengths' (p. 428)",
"coefficients": {
"a": "5.547e-4",
"c2": "5.15e5",
"c4": "4.19e11",
"c6": "4.09e17",
"c8": "4.32e23"
},
"check": "Static limit 11.084 a.u. (Table 2: 11.080). Lorentz-Lorenz at Loschmidt's number with a0^3 = 1.482e-25 cm^3. Checked 2026-09-24."
}
A Cauchy series in S(-2k); the paper’s form of n^2 - 1 (Eq. 2), not n - 1. Truncated where printed (’...’).
dalgarno_1960/n2_minus_1_Kr#
{
"id": "n2_minus_1_Kr",
"material": "Kr",
"equation": "unnumbered, p. 428",
"printed": "n^2 - 1 = 8.377 x 10^-4 (1 + 6.70 x 10^5/lambda^2 + 8.84 x 10^11/lambda^4 + 1.49 x 10^18/lambda^6 + 2.74 x 10^24/lambda^8 + 5.10 x 10^30/lambda^10 + ...)",
"variable": "lambda: wavelength in Angstrom (medium not stated; the fitted data mix the 1910 air and the 1932 vacuum wavelengths, a difference of 3e-4 in lambda)",
"state": "1atm_0C",
"density": "ideal",
"range": "the Cuthbertsons' visible and near-UV data; 'values in harmony with the available experimental data at all wavelengths' (p. 428)",
"coefficients": {
"a": "8.377e-4",
"c2": "6.70e5",
"c4": "8.84e11",
"c6": "1.49e18",
"c8": "2.74e24",
"c10": "5.10e30"
},
"check": "Static limit 16.737 a.u. (Table 2: 16.734). Lorentz-Lorenz at Loschmidt's number with a0^3 = 1.482e-25 cm^3. Checked 2026-09-24."
}
A Cauchy series in S(-2k); the paper’s form of n^2 - 1 (Eq. 2), not n - 1. Truncated where printed (’...’).
dalgarno_1960/n2_minus_1_Xe#
{
"id": "n2_minus_1_Xe",
"material": "Xe",
"equation": "unnumbered, p. 428",
"printed": "n^2 - 1 = 1.366 x 10^-3 (1 + 9.02 x 10^5/lambda^2 + 1.81 x 10^12/lambda^4 + 4.89 x 10^18/lambda^6 + 1.45 x 10^25/lambda^8 + 4.34 x 10^31/lambda^10 + ...)",
"variable": "lambda: wavelength in Angstrom (medium not stated; the fitted data mix the 1910 air and the 1932 vacuum wavelengths, a difference of 3e-4 in lambda)",
"state": "1atm_0C",
"density": "ideal",
"range": "the Cuthbertsons' visible and near-UV data; 'values in harmony with the available experimental data at all wavelengths' (p. 428)",
"coefficients": {
"a": "1.366e-3",
"c2": "9.02e5",
"c4": "1.81e12",
"c6": "4.89e18",
"c8": "1.45e25",
"c10": "4.34e31"
},
"check": "Static limit 27.29 a.u. (Table 2: 27.292). Lorentz-Lorenz at Loschmidt's number with a0^3 = 1.482e-25 cm^3. Checked 2026-09-24."
}
A Cauchy series in S(-2k); the paper’s form of n^2 - 1 (Eq. 2), not n - 1. Truncated where printed (’...’).
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.