gerardo_1974#
J. B. Gerardo and A. W. Johnson, “Photoattenuation in the extreme red wings of Xe and Kr resonant lines”, Phys. Rev. A 10, 1204 (1974)
Source record · Catalogue · Review register
Source kind: measurement
Recorded technique: VUV transmission of high-pressure Xe and Kr (Sandia): a dc capillary discharge in about 100 Torr of the same gas as the source, a 1 m McPherson 225 monochromator (1200 lines/mm, 0.83 A FWHM pass band), a 73.3 cm stainless-steel cell with baffles, an EMR 541F photomultiplier (signal stable to 1 %). Gas to 2.6e4 Torr, purified over hot Ti (O2, H2O below 1 ppm), at 273, 300 and 373 K; densities from the virial equation of state. The transmission is fitted by I = I_0 exp[-(k_s N + k_a N^2) l] (Eq. (1)) at 2000-20000 cm-1 to the red of the first resonance line (Xe 68045.66 cm-1, Kr 80917.56 cm-1).
Materials in structured entries: Kr, Xe
Dataset quantities: oscillator_strength
Contents: 2 datasets; 0 formulas.
Curation notes#
Journal pages 1204-1211 = PDF pages 1-8; the PDF is a scan. Identity checked against the first page.
WHAT IS MEASURED (pp. 1-3). k_s (cm^2), the attenuation per atom linear in N, and k_a (cm^5), the part quadratic in N, against nu_0 - nu from 2000 to 20000 cm-1 (Xe about 151-208 nm, Kr 126-164 nm), at 273, 300, 373 K (Xe) and 297, 373 K (Kr): Figs. 3 and 4 (with Shardanand’s k_s for 300 K Xe below 3400 cm-1), Fig. 5 (both gases at 373 K). k_a is measured down to 1e-45 cm^5 (Kr to 9000 cm-1); for 273 K Xe beyond 5800 cm-1 the data do not follow Eq. (1). The error bars of the figures are the accuracy of the fit of Eq. (1); no other uncertainty is stated.
INTERPRETATION (pp. 3-5). Within 7000 cm-1 of the line, k_a is absorption by unbound Xe2 and Kr2 pairs (vertical transitions from the repulsive ground state; quasistatic theory, Eqs. (9)-(12), giving the lower-state potential, the well depth of the bound upper state, at least 0.6 eV for Xe2* and 0.65 eV for Kr2*, and the Einstein coefficient: Figs. 7-9). Beyond it k_a, and k_s at all detunings, are mainly scattering: the macroscopic Rayleigh scattering of the index fluctuations, Eq. (3) (Landau and Lifshitz), with Eq. (5) and a Beattie-Bridgeman equation of state (Eq. (4), constants in Table I) giving k_s = 330 lambda^-4 N^-2 (n - 1)^2 (Eq. (7a), cgs: 32 pi^3/3 = 330.7, the dilute-gas Rayleigh cross section) and k_a = 1.1e-18 (-B_0 + A_0/RT + C/T^3) lambda^-4 N^-2 (n - 1)^2 (Eq. (8a), the pair term from the second virial coefficient), with (n - 1) from Eq. (6), a sum over oscillator strengths (Eqs. (7b), (8b)). The calculated k_s of Fig. 3 uses the two resonance lines (Table II) and McGuire’s approximate higher lines and continuum, f/lambda(A) = 0.75/1020, 0.67/970, 0.5/920, 0.41/876, 0.32/835, 0.25/800, 0.75/560 (p. 5), which give a static n - 1 ‘about 30 % lower than the measured value’; the open circles of Fig. 3 use measured n - 1 (Chashchina and Shreider). The measured k_s depends on temperature (373 K above 300 K), which the model does not explain: other scattering processes also contribute.
COMPARISON (read by eye from Fig. 3, not data): the 300 K xenon k_s, about 1e-23 cm^2 at 7000 cm-1, 5e-24 at 12000 and 2e-24 at 20000, matches the Rayleigh cross section of fit/Xe per atom, (8 pi/3) k^4 (alpha/4 pi eps0)^2 = 1.09e-23, 5.26e-24 and 2.01e-24 cm^2 at 163.8, 178.4 and 208.1 nm (TC-716). As sigma goes as alpha^2 and the figure is a log plot, this tests alpha only to 5-10 %.
NOT TRANSCRIBED: Figs. 2-9 (images; k_s, k_a and the derived potentials, figure only). k_s is an attenuation cross section (scattering and absorption), not purely the Rayleigh cross section of the vocabulary, and k_a (per N^2) has no quantity. Table I (Beattie-Bridgeman constants of Kr and Xe, from Cook’s compilation) is an equation of state, not an optical property. The Rayleigh (Eq. (2)) and refractivity (Eq. (6)) formulas are textbook relations.
DATASETS: table2_Xe and table2_Kr, Table II’s oscillator strengths of the 3P1 and 1P1 resonance lines (Xe 1470 and 1296 A, Kr 1236 and 1165 A, as printed, rounded), each from two references: 22 = P. G. Wilkinson 1966, 23 = D. K. Anderson 1965, 24 = E. L. Lewis 1967. Reproduced; the originals are not in the library. Laporte et al. 1975 (laporte_1975, Table I) give the same Wilkinson and Anderson values for Xe and Kr 123.6 nm, and attribute Kr 0.204 to Vaughan 1968, not Lewis.
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
gerardo_1974/table2_Xe#
{
"id": "table2_Xe",
"material": "Xe",
"file": "Xe/gerardo_1974__table2_Xe.csv",
"table": "tbl_5fe8d04e80c5",
"quantity": "oscillator_strength",
"abscissa_unit": "angstrom",
"wavelength_medium": "vacuum",
"use": "reproduced",
"reproduced_from": [
"P. G. Wilkinson, J. Quant. Spectrosc. Radiat. Transfer 6, 823 (1966)",
"D. K. Anderson, Phys. Rev. 137, A21 (1965)"
]
}
Table II: Xe 3P1 (1470 A as printed; 146.96 nm) 0.26 (ref22 Wilkinson), 0.256 (ref23 Anderson); 1P1 (1296 A; 129.56 nm) 0.27, 0.238. Wavelengths rounded to 1 A. Reproduced; no uncertainties.
gerardo_1974/table2_Kr#
{
"id": "table2_Kr",
"material": "Kr",
"file": "Kr/gerardo_1974__table2_Kr.csv",
"table": "tbl_5fe8d04e80c5",
"quantity": "oscillator_strength",
"abscissa_unit": "angstrom",
"wavelength_medium": "vacuum",
"use": "reproduced",
"reproduced_from": [
"E. L. Lewis, Proc. Phys. Soc. London 92, 817 (1967)",
"P. G. Wilkinson, J. Quant. Spectrosc. Radiat. Transfer 6, 823 (1966)"
]
}
Table II: Kr 3P1 (1236 A as printed; 123.58 nm) 0.204 (ref24 Lewis), 0.158 (ref22 Wilkinson); 1P1 (1165 A; 116.49 nm) 0.184, 0.135. Wavelengths rounded to 1 A. Reproduced; no uncertainties. NIST’s 0.205 and 0.189 (the fit/Kr priors) are close to Lewis’s.
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.