pindzola_1975#
M. S. Pindzola and H. P. Kelly, “Two-photon ionization of the neutral argon atom”, Phys. Rev. A 11, 1543-1551 (1975)
Source record · Catalogue · Review register
Source kind: theory
Recorded technique: Many-body perturbation theory: a double perturbation expansion in the Coulomb correlations and the atom-radiation interaction (Brueckner-Goldstone linked diagrams, Eqs. 14-20), for two-photon ionisation of the Ar 3p shell below the one-photon threshold. Lowest order: the diagrams of Figs. 1(a) and 1(b), Eq. 25, with the sums over intermediate states done explicitly over Hartree-Fock V^(N-1) bound (ten or so per l, the rest by the n^-3 rule) and continuum single-particle states (76-point k mesh, radial cut-off R = 20.365 bohr, checked against the closed sum rule of Eq. 27, Table I); final continuum orbitals in the HF V^(N-1) potentials of the kf 1D, kp 1D and kp 1S states. Third order (kf 1D only): intrashell ground-state correlations (Figs. 5(a), 5(b)) and the l’’ = 0 intermediate-state diagram of Fig. 5(c). Length and velocity forms; linear polarisation. ‘experimental values from Moore’s tables are used for all bound excited-state single-particle energies. The ionization energy of the 3p state is 0.579 a.u. (15.755 eV)’ (p. 5/1547).
Materials in structured entries: Ar
Dataset quantities: multiphoton_ionization_cross_section
Contents: 8 datasets; 0 formulas.
Curation notes#
Journal pp. 1543-1551 = PDF pages 1-9; journal page = PDF page + 1542. Identity checked on the first page (PDF p. 1: Phys. Rev. A 11, 1543, ‘Two-photon ionization of the neutral argon atom’; Michael S. Pindzola and Hugh P. Kelly, University of Virginia; received 20 January 1975) on 2026-10-09. The PDF is a scan: every page is one embedded 1-bit image, 4938 x 6686 pixels (about 580 dpi).
THE QUANTITY (Eq. 24, p. 4/1546): ‘sigma = 16 pi^2 F / (omega^2 c^2 k) |...|^2’, ‘where F = nc is the photon flux’, so sigma is proportional to F; the figures plot ‘sigma/F (10^-18 cm^2/a.u.)’, ‘cm^2/a.u. of flux’ in the captions: the generalised two-photon cross section, W = (sigma/F) F^2. One atomic unit of flux is 1/(a0^2 t0) = 1.4763e33 photons cm^-2 s^-1 (the text: ‘a flux F of 10^32 photons/cm^2 sec (0.07 a.u.)’, p. 8/1550, 0.068 by this), so a printed unit is 1e-18 cm^2 a0^2 t0 = 6.7736e-52 cm4 s (CODATA 2018), the datasets’ scale; the paper prints no such factor. ‘Calculations were carried out for linear polarization ... For circular polarization the kf 1D and kp 1D results are multiplied by 3/2 while the kp 1S final state is forbidden’ (p. 5/1547).
ENERGY AXIS: the photon energy omega, eV. ‘In order to have the energies for the resonances and thresholds agree as closely with experiment as possible, experimental values from Moore’s tables are used for all bound excited-state single-particle energies’ (p. 5/1547): the resonances stand at the experimental 4s 1P (11.62 eV), 5s 1P (14.09) and 3d 1P (14.15 eV) and the thresholds at 7.88 and 15.755 eV, drawn as vertical lines; the photoelectron energy is k^2/2 = epsilon_3p + 2 omega (Eq. 26). The resonance peaks are drawn ‘to infinity since Eq. (25) is evaluated without including shifts and widths’. ‘Points were calculated for Figs. 2-4 and 6 at intervals of 0.5 eV starting at omega = 8.0 eV’ (p. 5/1547), and ‘Calculations were not carried out beyond omega = D’ (14.15 eV; Fig. 2 caption): the curves join those points, and the values are read at them only. Fig. 3’s last x tick is labelled ‘18’; it is the 16 eV tick (evenly spaced with the others; Fig. 2 labels it 16).
EXTRACTED (tools/extract/pindzola_1975.py, with the reading machinery of tools/extract/pan_1990b.py), by data rule 8 (TC-699): the paper prints no value of the cross sections. Fig. 2 (kp 1D), Fig. 3 (kp 1S) and Fig. 4 (kf 1D): second-order length (L) and velocity (V); Fig. 6: kf 1D with the third-order correlations, LGI and VGI. Each read from the page image at its native resolution: the tick marks inside the four sides of the frame found in the image and on one linear scale per side within 3.1 pixels; the photon energy interpolated between the bottom and top ticks’ scales and the value between the left and right ones (the scan is rotated by up to 0.3 degrees); each curve traced from a seed pixel and its style checked (solid: no gap; dashed: gaps with nothing in them); a value where the line is clear of every other dark pixel within 6 pixels, no steeper than 3 pixels per column. Where another curve, the axis or a resonance line comes closer, the point is left out; where two curves of a figure are read within 7 pixels of each other both are left out; the script lists both and fails if they change. Each value’s pixel is in its printed cell. One pixel is 0.0056 eV in x; in y 0.0114 printed units (Figs. 2, 3) and 0.0228 (Figs. 4, 6); the lines are 4 to 6 pixels wide. The overlays of the values on the page images were inspected (2026-10-09).
DIGITISING UNCERTAINTY: 4 pixels in y: 0.05 printed units (3.4e-53 cm4 s) in Figs. 2 and 3, 0.1 (6.8e-53 cm4 s) in Figs. 4 and 6. The paper states no uncertainty; Table I’s sum-rule test (L(kl) against the closed integral <kl|z^2|3p>, six energies) differs by up to 0.09 a.u. in the radial values, and the replacement of the 5s-4d length elements near the 5s and 3d resonances is ‘an approximate procedure since it disturbs (a 1-30% effect) the balance’ (pp. 5-6).
THE CHECKS (the script fails if one is missed): (1) the vertical lines drawn on the calibrated axes against the energies the text prints: 4s 1P 11.613-11.624 eV (11.62), 5s 1P 14.088-14.089 (14.09), 3d 1P 14.135-14.144 (14.15), single-photon threshold 15.747-15.761 (15.755), threshold A 7.876 (7.88, Fig. 3; elsewhere the A line is too short to find); Fig. 6’s line C, 13.82 eV, is the 3d 1D autoionising resonance whose energy is not printed. (2) Fig. 6’s L and V (Fig. 4’s curves drawn again, read for this check only) against Fig. 4’s: L 0.998-1.009 (9 points), V 0.993-1.012 (12 points).
REPORTED (the script; at the computed points where the three channels are all read): the second-order length total, Figs. 2 + 3 + 4, is 1.24e-50 cm4 s at 8.0 eV, 1.21e-50 at 8.5, 1.17e-50 at 9.0, 1.02e-50 at 12.5 and 1.01e-50 at 13.0; the velocity total 7.3e-51 (8.0), 6.9e-51 (8.5), 6.6e-51 (9.0), 5.8e-51 (12.5). Against McKenna and van der Hart 2004 (mckenna_2004/fig5_sigma2_Ar, TC-856): length 0.98 (8.0 eV), 0.94 (9.0); velocity 0.57, 0.53. Against Pan, Gao and Starace 1990’s final length total (pan_1990b): length 1.27 at 9.0 eV. Against Moccia, Rahman and Rizzo 1983 (moccia_1983): length over their length 1.07 at 9.0 eV, their velocity 1.6 (8.0) and 1.36 (9.0); this paper’s velocity over theirs 0.94 and 0.77. Moccia et al. say this paper’s Ar results ‘agree pretty well with the present results’ (moccia_1983 notes); Pan et al. and Starace and Jiang redraw a total combined from this paper’s channels (not read there).
NOT TAKEN: (a) Fig. 4’s LG and VG (second order plus intrashell ground-state correlations, dashed): the two run within a few pixels of each other from 8.5 to 13.5 eV and cross twice, so which is which cannot be told reliably from the drawing; Fig. 6’s LGI and VGI carry the same correlations and more. (b) Fig. 4’s AHF and AHY: approximations of Bebb and Gold’s kind (Eq. 28, a mean excitation energy), ‘in very poor agreement’ with Eq. 25 (p. 6/1548), with HF and hydrogenic orbitals. (c) Table I (radial matrix elements L(kl) and <kl|z^2|3p> at 9-15.25 eV, a.u.): no quantity; it tests the continuum sum. (d) The fourth-order radiative correction (Eq. 29), evaluated but not drawn; the text’s statement that it ‘begin[s] to significantly affect’ the kf 1D result at a flux of about 1e32 photons cm^-2 s^-1 (0.07 a.u.) is not a value of a quantity. (e) The points not read (the datasets list them).
TWO-PHOTON REFERENCES the paper cites (data not in this record): W. Zernik, Phys. Rev. 135, A51 (1964) (H 2s); H. B. Bebb and A. Gold, Phys. Rev. 143, 1 (1966) (H, 2-12 photons; the rare gases at the ruby line only, 7-14 photons; bebb_1966, TC-995); H. B. Bebb, Phys. Rev. 149, 25 (1966) and 153, 23 (1967) (alkalis); V. M. Morton, Proc. Phys. Soc. London 92, 301 (1967); Y. Gontier and M. Trahin, Phys. Rev. 172, 83 (1968), Phys. Rev. A 7, 1899 and 2069 (1973); C. S. Chang and P. Stehle, Phys. Rev. A 4, 641 (1971); P. Lambropoulos, Phys. Rev. A 9, 1992 (1974); S. Geltman, Phys. Lett. 4, 168 (1963) (negative ions); measured, alkalis: R. A. Fox, R. M. Kogan and E. J. Robinson, Phys. Rev. Lett. 26, 1416 (1971); G. A. Delone, N. B. Delone and G. K. Piskova, Sov. Phys. JETP 35, 672 (1972).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
pindzola_1975/fig2_L_p1D_Ar#
{
"id": "fig2_L_p1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig2_L_p1D_Ar.csv",
"table": "fig_4c9504d1d62e",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.05,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "length",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kp 1D"
}
}
Fig. 2 (p. 6/1548), L (solid): the 3p5 kp 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, length form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0, 8.5, 9.0, 12.5 and 13.0 eV; 0.45 to 3.36 (from 9.5 to 11 eV it runs into the axis together with V; 12.0 on the 4s flank; from 13.5 into the 3d rise). +-0.05 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig2_V_p1D_Ar#
{
"id": "fig2_V_p1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig2_V_p1D_Ar.csv",
"table": "fig_4c9504d1d62e",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.05,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "velocity",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kp 1D"
}
}
Fig. 2 (p. 6/1548), V (dashed): the 3p5 kp 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, velocity form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0, 8.5, 9.0 and 12.5 eV; 0.71 to 2.87. +-0.05 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig3_L_p1S_Ar#
{
"id": "fig3_L_p1S_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig3_L_p1S_Ar.csv",
"table": "fig_7688b2052b30",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.05,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "length",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kp 1S"
}
}
Fig. 3 (p. 6/1548), L (solid): the 3p5 kp 1S partial two-photon ionisation cross section of Ar 3p, linear polarisation, length form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0 to 11.0 and 12.5 to 13.5 eV; 0.55 to 8.34. +-0.05 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig3_V_p1S_Ar#
{
"id": "fig3_V_p1S_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig3_V_p1S_Ar.csv",
"table": "fig_7688b2052b30",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.05,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "velocity",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kp 1S"
}
}
Fig. 3 (p. 6/1548), V (dashed): the 3p5 kp 1S partial two-photon ionisation cross section of Ar 3p, linear polarisation, velocity form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0 to 10.5 and 12.5 eV; 0.26 to 4.45 (from 13.0 to 13.5 eV it runs along the axis). +-0.05 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig4_L_f1D_Ar#
{
"id": "fig4_L_f1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig4_L_f1D_Ar.csv",
"table": "fig_17415fef50fa",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.1,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "length",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kf 1D"
}
}
Fig. 4 (p. 6/1548), L (solid): the 3p5 kf 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, length form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0 to 9.0 and 10.0 to 13.5 eV; 6.65 to 13.95 (9.5 eV, where the AHF curve crosses, left out); drawn again in Fig. 6, which agrees within 1 %. +-0.1 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig4_V_f1D_Ar#
{
"id": "fig4_V_f1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig4_V_f1D_Ar.csv",
"table": "fig_17415fef50fa",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.1,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "velocity",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order: the diagrams of Figs. 1(a) and 1(b)",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kf 1D"
}
}
Fig. 4 (p. 6/1548), V (solid): the 3p5 kf 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, velocity form, second order, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 8.0 to 13.5 eV; 3.41 to 8.09; drawn again (dashed) in Fig. 6, which agrees within 1.2 %. +-0.1 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig6_LGI_f1D_Ar#
{
"id": "fig6_LGI_f1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig6_LGI_f1D_Ar.csv",
"table": "fig_e8afb9fc4099",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.1,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "length",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order plus third-order intrashell ground-state correlations (Figs. 5(a), 5(b)) and the intrashell intermediate-state diagram of Fig. 5(c) with l'' = 0, which brings in the 4s and 5s 1P resonances",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kf 1D"
}
}
Fig. 6 (p. 7/1549), LGI (solid): the 3p5 kf 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, length form, with intrashell ground-state and intermediate-state correlations, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 9.5 to 11.0, 12.0 and 12.5 eV; 9.09 to 11.80 (8.0 to 9.0 and 13.0 to 13.5 eV, where LGI and VGI run within a line width of each other, left out of both). +-0.1 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
pindzola_1975/fig6_VGI_f1D_Ar#
{
"id": "fig6_VGI_f1D_Ar",
"material": "Ar",
"file": "Ar/pindzola_1975__fig6_VGI_f1D_Ar.csv",
"table": "fig_e8afb9fc4099",
"digitised": "raster",
"quantity": "multiphoton_ionization_cross_section",
"unit": "cm4 s",
"scale": 6.7736e-52,
"abscissa_unit": "eV",
"use": "check",
"uncertainty": {
"absolute": 0.1,
"level": "not stated"
},
"parameters": {
"photons": 2,
"polarization": "linear",
"gauge": "velocity",
"method": "many-body perturbation theory (Brueckner-Goldstone diagrams), explicit sum over HF V^(N-1) bound (ten or so per l, then the n^-3 rule) and continuum (76-point k mesh, radial cut-off R = 20.365 bohr; 90.0 bohr for the 5s, 6s, 3d, 4d length elements near the 5s and 3d resonances) intermediate states; experimental (Moore) bound excited-state energies and 3p ionisation energy 0.579 a.u. (15.755 eV); photoelectron energy k^2/2 = epsilon_3p + 2 omega (Eq. 26); second order plus third-order intrashell ground-state correlations (Figs. 5(a), 5(b)) and the intrashell intermediate-state diagram of Fig. 5(c) with l'' = 0, which brings in the 4s and 5s 1P resonances",
"definition": "sigma/F, the cross section of Eq. 24 (sigma proportional to the photon flux F = nc) over F, printed in 10^-18 cm^2 per atomic unit of flux; times 1e-18 cm^2 a0^2 t0 = 6.7736e-52 it is the generalised cross section in cm4 s, W = (sigma/F) F^2 with F in photons cm^-2 s^-1 (the record's notes)",
"channel": "3p5 kf 1D"
}
}
Fig. 6 (p. 7/1549), VGI (dashed): the 3p5 kf 1D partial two-photon ionisation cross section of Ar 3p, linear polarisation, velocity form, with intrashell ground-state and intermediate-state correlations, sigma/F in 10^-18 cm^2 per a.u. of flux (scale to cm4 s) against the photon energy, read from the scanned image at the computed points (every 0.5 eV from 8.0 eV, p. 5/1547), 9.5 to 11.5, 12.0 and 12.5 eV; 9.60 to 11.38. +-0.1 x 10^-18 cm^2/a.u. (printed unit): the reading (4 pixels; the record’s notes); the paper states none.
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.