gornik_1981#
W. Gornik, S. Kindt, E. Matthias and D. Schmidt, “Two-photon excitation of xenon atoms and dimers in the energy region of the 5p5 6p configuration”, J. Chem. Phys. 75, 68-74 (1981)
Source record · Catalogue · Review register
DOI: 10.1063/1.441856
Source kind: measurement
Recorded technique: Two-photon excitation of xenon (10^-6 to 1.3 bar, room temperature) by a frequency-doubled pulsed dye laser (Coumarin 307, 480-520 nm, 0.01 nm (12 GHz), 5 ns, 70 kW, 30 Hz; doubled in LFM to 300 W, bandwidth 18 GHz, ‘about 2 MW/cm2’ at the focus), scanned over 246-260 nm; the VUV fluorescence on a solar-blind photomultiplier (photon counting, or the current for the strong atomic lines) or the near-infrared 6p -> 6s fluorescence (823.2 nm for 6p[3/2]2), the UV energy recorded shot by shot. The absolute rate of 6p[3/2]2 at 2.6 ubar with ‘a reduced laser bandwidth of 2.8 GHz’ and ‘an estimated power density of 1.8 MW/cm2’ (p. 70); the other two from relative line intensities. Pressure shifts against a 2 mbar reference cell (Fig. 5).
Materials in structured entries: Xe
Dataset quantities: pressure_line_coefficient
Contents: 2 datasets; 0 formulas.
Curation notes#
J. Chem. Phys. 75(1), 68-74 (1 July 1981) = PDF pages 2-8 (PDF page 1 is the AIP download cover; journal page = PDF page + 66). Identity checked against the first page of the article (PDF p. 2: title, authors, Freie Universität Berlin; received 30 January 1981, accepted 10 March 1981) on 2026-10-08. Every number below was read on the rendered pages (pp. 70-71) and Table I’s image. The paper writes the jl labels with vertical bars (6p|3/2|2 for 6p[3/2]2).
TAKEN (after TC-1040, pressure_line_coefficient): the pressure shifts and broadening below (PRESSURE EFFECTS). NO TWO-PHOTON STRENGTH IS TAKEN. The paper’s two-photon results are transition rates, not cross sections: - ‘W(1S0 -> 6p|3/2|2) = 3.5 x 10^3 s-1’, ‘accurate within a factor of 3, due to uncertainties in the quantum efficiency of the detector and geometrical factors’ (p. 70), and the ratios 6p[1/2]0 : 6p[5/2]2 : 6p[3/2]2 = 9 : 5 : 1, ‘about 20%’ (laser intensity fluctuations). Table I (p. 71), ‘Measured and estimated two-photon transition rates for I0 = 1.8 MW/cm2 and Delta omega / 2 pi = 4 GHz’: measured 3.2 x 10^4, 3.5 x 10^3, 1.8 x 10^4 s-1 and single-path estimates 1.2 x 10^4, 5.1 x 10^3, 1.3 x 10^4 s-1 for 6p[1/2]0 (249.63 nm), 6p[3/2]2 (252.48 nm), 6p[5/2]2 (256.01 nm). - A rate at one intensity and one bandwidth is not a quantity of the vocabulary; converting it to two_photon_excitation_cross_section needs the intensity’s spatial and temporal averaging, which the paper does not give (an ‘estimated power density’), and is not done here. For comparison only: the paper’s own line shape (the estimate’s expression on p. 70: a Gaussian of FWHM Delta omega with Delta omega^2 = 2 Delta omega_L^2 + Delta omega_D^2, peak (4 ln 2 / pi)^(1/2) / Delta omega, unit area in the two-photon angular frequency, and a factor 2 for ‘temporal fluctuations of the laser intensity’, i.e. G2 = 2) with Delta omega / 2 pi = 4 GHz and I0 = 1.8 MW/cm2 turns the measured rates into sigma G2 = W / (g Phi^2) = 16.7, 1.79 and 8.95 x 10^-35 cm4 (6p[1/2]0, 6p[3/2]2, 6p[5/2]2), or 8.4, 0.89 and 4.5 x 10^-35 with G2 = 2 divided out. Checked: Table I’s Delta omega / 2 pi = 4 GHz is the absorption-line FWHM of the 2.8 GHz laser of the absolute measurement without the Doppler term, sqrt(2) x 2.8 = 3.96 GHz (Delta omega^2 = 2 Delta omega_L^2 + Delta omega_D^2; the Doppler width used is not stated). The geohegan_1986 quote is checked in the convention W = alpha I^2 / hbar omega (below). - The derived Delta C6 and C6 (Table II, p. 72), the Xe2 band positions (Table III): no quantity.
PRESSURE EFFECTS (p. 72, Figs. 5-6, Table II; image of Table II checked cell by cell; tools/extract/gornik_1981.py). Self-perturbed (pure xenon, 10^-3 to 1.3 bar, room temperature, not stated as a number), the peaks measured against a 2 mbar reference cell. TAKEN: Table II’s ‘Shift beta/N (10^-9 s^-1 cm^3)’, -2.5 (0.2), -2.7 (0.2), -2.8 (0.2) for 1S0 -> 6p[1/2]0, 6p[3/2]2, 6p[5/2]2, ‘beta is the line shift in angular frequencies and N the number of atoms per cm^3’ (beta_shift_Xe, primary; equal to the abstract’s values, script check); and the linewidth’s pressure dependence for 6p[1/2]0, ‘(~25 MHz/Torr)’ from Fig. 6 (p. 72), which the authors did not deconvolve (‘Lacking knowledge of the precise spectral profile of the laser prevents us from deconvoluting the observed line shape to determine the broadening parameter 2 gamma / N’), inline (broadening_Xe, check). FREQUENCY SCALE: the transition’s (two-photon) frequency, by the paper’s own numbers: beta/N = -2.5e-9 s^-1 cm^3 is -9.8 GHz/bar in ordinary frequency at 295 K (script), the slope of Fig. 5’s 6p[1/2]0 line (0 to about -15 GHz over 1.5 bar, read by eye); Figs. 5 and 6 share the axis unit, and Fig. 6’s zero-pressure width, ‘the expected value of around 30 GHz’, is the two-photon-scale width of the 18 GHz laser, sqrt(2) x 18 = 25 GHz with the 2.6 GHz Doppler term, not the 18 GHz the laser scale would give; and Delta C6 is derived from beta as the ground-6p difference potential. The paper does not state the scale in words. Sign as printed: negative, a red shift. In ordinary frequency at 295 K the shifts are -13.0, -14.1, -14.6 MHz/torr (script). Not taken: Hawkins et al.’s ‘(25 +- 15) MHz/Torr’, quoted as gamma / (pi p) (hawkins_1980 holds it); Fig. 4 (line shapes).
FINDING: kroll_1990 (TC-890) and raymond_1984. Kroll and Bischel’s Table I lists this paper (their Ref. 8) as sigma_tot G2(0) = 6.8, 0.74 and 3.7 x 10^-35 cm4 (‘Factor of 3’). Those numbers are raymond_1984’s Table I values for this paper, 108, 12 and 61 cm4/J^2 (‘inferred from their measured transition rates’), multiplied by (hbar omega)^2 at 249.63, 252.48 and 256.01 nm (6.84, 0.743, 3.67 x 10^-35): Kroll and Bischel took them from Raymond et al., not from this paper. Raymond et al.’s values correspond to g = W / (alpha I0^2) = 9.1 x 10^-11 s for all three levels at I0 = 1.8 MW/cm2, 2.4 times this paper’s own 3.74 x 10^-11 s; the step is not given and is not reproduced here. So the ‘Ref. 8’ row of kroll_1990 is 2.4 times below what this paper’s printed rates give with its own stated line shape, intensity and bandwidth (the ratios between the levels agree). Neither copy states the G2(0) convention: this paper’s rates include the factor 2 of chaotic light.
FINDING: geohegan_1986 (TC-886). It quotes this paper for the two-photon excitation of Xe 6p[3/2]2 as ‘alpha ~ 1.2 x 10^-27 cm4 W-1’ (its p. 275). In that convention (W = alpha I^2 / hbar omega, bokor_1980’s Eq. 1) the measured 3.5 x 10^3 s-1 at 1.8 MW/cm2 and 252.48 nm gives 8.5 x 10^-28, the single-path estimate 5.1 x 10^3 s-1 gives 1.24 x 10^-27: the quoted value is the estimate, not the measurement.
TWO-PHOTON DATA CITED, NOT IN THE LIBRARY (Hawkins et al. 1980, the broadening’s source, is now hawkins_1980; Gornik et al. 1980 is gornik_1980): B. Cagnac, G. Grynberg and F. Biraben, J. Phys. (Paris) 34, 845 (1973) and G. Grynberg and B. Cagnac, Rep. Prog. Phys. 40, 791 (1977) (theory); K. Aron and P. M. Johnson, J. Chem. Phys. 67, 5099 (1977) (multiphoton ionisation of Xe and Xe2).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
gornik_1981/beta_shift_Xe#
{
"id": "beta_shift_Xe",
"material": "Xe",
"file": "Xe/gornik_1981__beta_shift_Xe.csv",
"table": "tbl_2928c3b46e82",
"quantity": "pressure_line_coefficient",
"unit": "cm3/s",
"scale": 1e-09,
"abscissa": "label",
"use": "primary",
"uncertainty": {
"column": true,
"level": "not stated"
},
"parameters": {
"effect": "shift",
"transition": "1S0 -> 6p|J|K (Table II's rows)",
"photons": 2,
"frequency_scale": "transition",
"width": "none",
"frequency_variable": "angular",
"perturber": "self",
"pressure_range": "1e-3 to 1.3 bar",
"method": "two-photon excitation spectra, the line maximum against a 2 mbar reference cell, linear fit to Fig. 5"
}
}
Table II (p. 72), ‘Shift beta/N (10^-9 s^-1 cm^3)’, the self-induced shifts of the two-photon lines from 1S0 to 6p[1/2]0, 6p[3/2]2, 6p[5/2]2 (NIST 5p5(2P*3/2)6p 2[1/2] J = 0, 2[3/2] J = 2, 2[5/2] J = 2), linear up to 1.3 bar (Fig. 5); beta in angular frequency on the transition’s scale (record notes), N in atoms per cm^3; negative = red. The bracketed uncertainty as printed, level not stated.
gornik_1981/broadening_Xe#
{
"id": "broadening_Xe",
"material": "Xe",
"table": "text",
"quantity": "pressure_line_coefficient",
"unit": "MHz/torr",
"abscissa": "label",
"use": "check",
"uncertainty": {
"level": "not stated"
},
"parameters": {
"effect": "broadening",
"transition": "1S0 -> 6p|1/2|0",
"photons": 2,
"frequency_scale": "transition",
"width": "not stated",
"frequency_variable": "ordinary",
"perturber": "self",
"pressure_range": "1e-3 to 1.5 bar (Fig. 6)",
"method": "slope of the observed linewidth against pressure (Fig. 6), not deconvolved from the laser profile"
}
}
1 inline points in the source record.
p. 72: ‘the pressure dependence of the linewidth in Fig. 6 (~25 MHz/Torr)’, 1S0 -> 6p[1/2]0, the observed width (laser 18 GHz, not deconvolved; the authors decline to give the broadening parameter 2 gamma / N); approximate. A check: it agrees with hawkins_1980’s 25 +- 15 MHz/Torr, as the paper says.
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.