mccann_1988

M. P. McCann, C. H. Chen and M. G. Payne, “Two-photon (vacuum ultraviolet + visible) spectroscopy of argon, krypton, xenon, and molecular hydrogen”, J. Chem. Phys. 89, 5429-5441 (1988)

Source record · Catalogue · Review register

DOI: 10.1063/1.455595

Source kind: measurement

Recorded technique: Two-colour two-photon excitation followed by ionisation, the photoelectrons collected on guarded parallel plates (2.54 cm) in a cell of Ar or Kr (below 55 Torr for the rate constants) or H2 (about 800 Torr). One photon fixed at 118 nm (VUV): the third harmonic of a frequency-tripled Nd:YAG laser (355 nm, 5-6 ns, Quanta-Ray DCR-1A with an intracavity etalon, the 1064 nm bandwidth under 0.2 cm-1), generated in about 30 Torr of xenon with a 15 cm lens through LiF windows, about 100 nJ per pulse (Table I, 1.2 to 462 nJ for 0.5 to 20 mJ of 355 nm, measured by photoionising NO). The other photon from a dye laser pumped by the same 355 nm, 400-700 nm, bandwidth 0.2 cm-1, focused with a 25 cm lens and counter-propagating; both lasers vertically polarised (p. 5430). The ionisation step (a further visible or 355 nm photon) saturated; K2 from the ion number with Eq. (25) for the two focused Gaussian beams (Eqs. 3-24). Xenon (Sec. V): ionised in the generation cell itself by one 355 nm and one 118 nm photon, the VUV measured in a second cell of 140 Torr NO.

Materials in structured entries: Xe

Dataset quantities: multiphoton_ionization_cross_section

Contents: 1 dataset; 0 formulas.

Curation notes

J. Chem. Phys. 89(9), 5429-5441 (1 November 1988) = PDF pages 2-14 (PDF page 1 is the AIP download cover; journal page = PDF page + 5427). Identity checked against the first page of the article (PDF p. 2: title, authors, Oak Ridge; received 11 April 1988, accepted 19 July 1988) on 2026-10-08. The library’s file is named ‘mccann-1989.pdf’ and hattig_1998b (TC-887) cites the paper as ‘J. Chem. Phys. 89, 5429 (1989)’: the year is 1988. Every number below was read on the rendered pages (pp. 5434-5436, 5438-5439) and Table II’s image.

WHAT IS TAKEN. The two-colour two-photon ionisation rate constant of xenon, one 118 nm and one 355 nm photon: ‘The two-photon ionization rate constant from this data was 3.5 x 10^-45 cm4 s. The bandwidth of the UV laser beam was 3.5 cm-1. This two-photon rate is enhanced by the fact that the VUV photon energy is just above the one-photon transition as shown in Fig. 4’ (p. 5436). It is a cross section of the continuum (the two photons, 10.5 + 3.5 eV, lie above xenon’s first ionisation threshold), multiphoton_ionization_cross_section with photons = 2, in the source’s unit; the paper gives no formula for this measurement, and cm4 s is a rate per product of the two photon fluxes, as K2 of Eq. (25) is ‘per VUV and visible photon’ (p. 5435). A check: non-degenerate (the record’s abscissa is the 118 nm photon, the 355 nm one in parameters), near-resonant with the VUV photon (so it depends on its exact wavelength), no uncertainty stated.

NOT TAKEN: TABLE II (Ar, Kr) AND TABLE III (H2). Two quantities per transition: K2, ‘two-photon rate constant (cm4 s)’ (Eq. 25), and T2, the ‘two-photon constant’, ‘T2 = K2 sqrt(Delta1^2 + Delta2^2)’ (Eq. 28), Delta1 and Delta2 the lasers’ FWHM bandwidths in rad/s, which ‘will have the units of cm4’ (p. 5439; Table II’s header prints ‘T2 (cm4 s2)’, a slip). Argon 3p5 4p and 4p’ levels (seven, J = 0, 1, 2; 105 611-107 495 cm-1), krypton 4p5 4f (three, J = 2; 105 961-107 410 cm-1), H2 E,F 1Sigma_g+ v’ = 3, 6-14 from v’’ = 0 (ten). Neither holds two_photon_excitation_cross_section: (a) K2 is the line-centre rate constant of these lasers (the rate per product of the photon fluxes), which depends on the bandwidths: not the frequency-integrated cross section (TC-872). (b) T2 is the frequency-integrated cross section only up to the line shape: for a two-photon profile of FWHM Delta = sqrt(Delta1^2 + Delta2^2), K2 = sigma-bar g(0), so T2 = sigma-bar g(0) Delta, and g(0) Delta is 2 sqrt(ln 2 / pi) = 0.939 for Gaussian lasers but 2 / pi = 0.637 for Lorentzian ones; the paper states no line shape. The bandwidths behind Table II are not stated either: T2 / K2 is 3.79-4.05 x 10^11 rad/s (2.0-2.15 cm-1) for every Ar and Kr row, not the 1.74 x 10^12 rad/s that Sec. IV’s Delta1 = 1.7 x 10^12 (VUV) and Delta2 = 3.77 x 10^11 rad/s (visible) give; and Delta2 is 2.0 cm-1 where Sec. II A gives the dye laser 0.2 cm-1. For H2, T2 / K2 is 2.6-5.4 x 10^11 rad/s, varying from row to row. The photon statistics of the two multimode pulsed beams (one a third harmonic) are not stated or corrected. (c) The pairs are non-degenerate (118 nm with a visible photon of about 410-590 nm), and the intermediate-state enhancement differs from that of a degenerate pair; the paper says so for H2 (p. 5438). The Ar 4p’[3/2]2 K2, 1.3 x 10^-47 cm4 s, is called ‘very close’ to the 1.7 x 10^-47 of Eq. (7) with a Hartree-Fock-type M2 = 1.7 (p. 5436; checked: 14 M2^2 / sqrt(Delta1^2 + Delta2^2) = 2.32 x 10^-11 s cm4 J-2 (printed 2.3), times the energies of a 118 nm photon and the visible one that completes 107 287 cm-1 (443.6 nm), 1.75 x 10^-47, printed 1.7). The values ‘have been corrected due to a revision in the VUV intensity’ (Ref. 55, IQEC 1987). Eq. (28) defines T2 with ‘K2 = two-photon rate constant defined in Eq. (16)’: Eq. (16) is a step of the ionisation-probability algebra; K2 is defined by Eqs. (7) and (25), a slip. The transition energies (in vacuo, ‘agree with the literature values within the bandwidth of the lasers’, p. 5436): not taken. Figs. 5-17 (VUV conversion, spectra): no further numbers. The literature H2 Q1(0,0) two-photon cross section, 1.5 x 10^-30 cm4 W-1 (Ref. 12, Marinero, Rettner and Zare 1982), quoted: not taken.

FINDING: hattig_1998b (TC-887) and sundholm_1994. Hättig et al.’s ‘experimental value of 2.05 x 10^-51 cm4 s’ for argon’s 1De level, ‘derived as the sum of the transition probability rates to’ the three J = 2 levels 4p[3/2]2, 4p[5/2]2 and 4p’[3/2]2, at omega_2 = 10.49 eV (118.2 nm, this paper’s VUV photon), is not printed here. It is sundholm_1994’s sum 1.4 + 0.53 + 0.12 x 10^-51 cm4 s (‘transition probability rates’ to 4p[5/2]2, 4p[3/2]2 and 4p’[3/2]2, citing this paper and Payne et al.), which are this paper’s Table II T2 (6.2, 2.2, 0.51 x 10^-35 cm4) times the atomic unit of time (2.418 884 x 10^-17 s): 1.500, 0.532 and 0.123 x 10^-51. The second and third are as sundholm_1994 prints them; the first is 7 % lower there (1.4 for 1.50), and the sum of the T2 t0 is 2.16 x 10^-51, 5 % above 2.05. So the 2.05 is this paper’s T2 in a form (T2 t0), with T2 the line-shape-ambiguous quantity of (b), one term misquoted, for a non-degenerate pair. Payne et al.’s papers (payne_1981, Chem. Phys. Lett. 79, 142 (1981); payne_1982, Adv. At. Mol. Phys. 17, 229 (1981)) print no argon rate constants (searched, 2026-10-09).

TWO-PHOTON DATA CITED, NOT IN THE LIBRARY: E. E. Marinero, C. T. Rettner and R. N. Zare, Phys. Rev. Lett. 48, 1323 (1982) (H2 E,F, 1.5 x 10^-30 cm4 W-1); M. P. McCann, C. H. Chen and M. G. Payne, IQEC Tech. Digest XV, 166 (1987) (the uncorrected values). The paper’s Payne et al. references are curated as payne_1981 and payne_1982.

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets

mccann_1988/sigma2_Xe_118_355

{
  "id": "sigma2_Xe_118_355",
  "material": "Xe",
  "table": "text",
  "scale": 1e-45,
  "quantity": "multiphoton_ionization_cross_section",
  "unit": "cm4 s",
  "abscissa_unit": "nm",
  "use": "check",
  "uncertainty": {
    "level": "not stated"
  },
  "parameters": {
    "photons": 2,
    "frequencies": "non-degenerate: one 118 nm photon (x) and one 355 nm photon",
    "second_wavelength_nm": 355,
    "polarization": "linear",
    "polarization_printed": "'The output of both the Nd:YAG and the dye laser had vertical polarization' (p. 5430); the 118 nm is the 355 nm beam's third harmonic",
    "method": "photoelectrons from the xenon of the third-harmonic generation cell (with argon for phase matching), the 118 nm energy from the photoionisation of NO in a second cell; parallel 355 nm beam",
    "definition": "rate = sigma Phi_118 Phi_355, Phi the photon fluxes in cm-2 s-1 (cm4 s, as printed; the paper gives no formula for this measurement)",
    "linewidth_cm1": 3.5,
    "linewidth_definition": "'The bandwidth of the UV laser beam was 3.5 cm-1' (p. 5436)"
  }
}

1 inline points in the source record.

p. 5436 (Sec. V): the two-photon ionisation rate constant of xenon for one 118 nm and one 355 nm photon, 3.5 x 10^-45 cm4 s, the UV bandwidth 3.5 cm-1. Non-degenerate: x is the 118 nm photon (the third harmonic of the 355 nm), the 355 nm one is in parameters. Enhanced by the nearness of the 118 nm photon to a one-photon transition (Fig. 4), so not comparable with a degenerate cross section at either wavelength. No uncertainty stated.

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.