gallagher_1988

J. W. Gallagher, C. E. Brion, J. A. R. Samson and P. W. Langhoff, “Absolute cross sections for molecular photoabsorption, partial photoionization, and ionic photofragmentation processes”, J. Phys. Chem. Ref. Data 17, 9 (1988)

Source record · Catalogue · Review register

DOI: 10.1063/1.555821

Source kind: compilation

Recorded technique: Compilation (JILA Data Center) of measured and calculated absolute total photoabsorption, electronic partial photoionisation and ionic photofragmentation cross sections and photoelectron asymmetry parameters of 21 molecules, from the first ionisation threshold to about 100 eV (some sets to 525 eV), published to the end of 1986 or privately communicated. Values ‘are extracted from journal and manuscript figures using standard digitization techniques, or read from tables, and entered into a data base’ (p. 27). The measured total photoabsorption sets are photon measurements (simple cell, split beam, double ion chamber; absolute by measuring I0/I, path and number density: ‘AB’) or dipole (e,e) electron energy-loss measurements (relative spectrum from the Bethe-Born factor, put on an absolute scale by the valence-shell Thomas-Reiche-Kuhn sum rule: ‘TRK’; or normalised at one energy to a known cross section: ‘NM’) (pp. 17-23, 27).

Materials in structured entries: None recorded.

Dataset quantities: None recorded.

Contents: 0 datasets; 0 formulas.

Curation notes

Journal pages 9-153 = PDF pages 2-146 (PDF page 1 is the publisher’s cover sheet, which is why the library’s author check fails; journal page = PDF page + 7). Identity checked against the first page (PDF page 2, journal p. 9): title, the four authors and J. Phys. Chem. Ref. Data Vol. 17, No. 1, 1988 agree with the citation and DOI.

NO DATASETS. The paper holds no numerical cross sections: Tables 2-19 (one per molecule) are lists of the data sources (reference, author, year, experiment or theory, method, normalisation, which cross sections, photon-energy range), and every cross section is given only as points (measured) or lines (calculated) in the figures, in Mb on the left axis and df/dE in 1e-2 eV^-1 on the right, with a top wavelength axis in nm and the ionisation threshold as a dotted line (pp. 27-28). There is no recommended or evaluated curve: all sets are plotted together, and the evaluation is the accuracy statement below. ‘A tabular listing of all data presented in the figures is available in JILA Data Center Report No. 32’ (p. 28): that report (not in the library) holds the numbers. The figures are not digitised here (numbers from tables only; a digitisation of a digitisation would add a third reading error). All plotted data are themselves reproductions of the original papers (or of private communications), none of which is a curated source.

Cross-section units (p. 17, Eq. 2.22): sigma [Mb] = (pi e^2 h / m c) df/dE [eV^-1] = 109.75 df/dE [eV^-1] (printed ‘109.75’). Quantity: the total photoabsorption cross section sigma_abs^T = sigma_n + sigma_ion^T (Eq. 2.7), neutral excitation plus ionisation, the optmat quantity absorption_cross_section. Temperature: not stated for the compilation (room-temperature gas in the original measurements).

Stated accuracy (p. 28): ‘In most cases, the original publications provide little direct information of the author’s assessment of accuracy of the measured data’; the agreement between the independent photon (absolute) and dipole (e,e) (TRK) methods is used as the criterion. ‘in almost all cases the absolute photoabsorption cross sections (sigma_abs^T) are considered to be accurate to better than +-10% over the energy ranges shown, and in many cases (N2, CO, O2, NO, CO2, N2O, H2O, NH3, CH4, H2S, CS2, COS), to better than +-5%. Examination of the figures shows that a few data sets may be less accurate than +-10% in certain energy ranges, particularly in the immediate threshold region.’ The largest errors ‘apparently occur as a result of uncertainties in the measurement of particle density’; for dipole (e,e): stray electrons, shell separation in the TRK normalisation, the extrapolation of the tail. Level not stated. Method statements: photon I0/I errors ‘should be limited to 1% or 2% in regions of continuous absorption’, larger in structured regions when the bandwidth exceeds the intrinsic widths (pp. 19-20); capacitance-manometer transpiration ‘errors of a few percent’ (p. 20); TRK normalisation ‘an accuracy of usually better than ~5%’, the tail beyond several hundred eV extrapolated as a eps^-b, b 2-2.5, usually <= 5 % of the area (p. 23). Partial cross sections: sigma_ion^j ‘accurate to within +-15% in most cases’ (p. 29), sigma_ion^frag ‘to within +-10% for all except the lowest abundance ions’ (p. 29).

Below about 20 eV (the ‘structured’ region between the first ionisation potential and ~20 eV) the plotted sets scatter strongly: autoionising structure sampled with different bandwidths (pp. 13-15 define the region and say a compilation there is ‘premature’; the discrete region below the first ionisation potential is not considered). The compilation is aimed at the smooth continuum above ~20 eV.

Per gas below: the total-photoabsorption rows of each source table (the ‘Abs’ column ticked; checked against the table images), the figure, and what the figure shows (read qualitatively from the figure image). Reference numbers and citations are the paper’s (checked against the reference-list page images, pp. 149-153). Ref. 236 is ‘J. A. R. Samson and G. Haddad (private communication)’: these sets exist only in this compilation (and Report No. 32).

CO (Table 5, p. 47, tbl_6ceb6d8518e8; Fig. 24, p. 48; stated accuracy better than +-5 %): Lee 1973 (ref. 208; L. C. Lee, R. W. Carlson, D. L. Judge and M. Ogawa, J. Quant. Spectrosc. Radiat. Transfer 13, 1023 (1973)), photon, AB, 20-70 eV; Watson 1975 (ref. 253; W. C. Watson, D. T. Stewart, A. B. Gardner and M. J. Lynch, Planet. Space Sci. 23, 384 (1975)), photon, AB, 20-35 eV; Wight 1976 (ref. 256; G. R. Wight, M. J. Van Der Wiel and C. E. Brion, J. Phys. B 9, 675 (1976)), dipole (e,e), TRK, 18-70 eV; de Reilhac 1977 (ref. 170; L. De Reilhac and N. Damany, J. Quant. Spectrosc. Radiat. Transfer 18, 121 (1977)), photon, AB, 25-118 eV; Cole 1978 (ref. 164; B. E. Cole and R. N. Dexter, J. Phys. B 11, 1011 (1978)), photon, AB, 36-83 eV; Samson 1984 (ref. 236, private communication), photon, AB, 14-125 eV. Fig. 24: (a) 10-45 eV, threshold line near 14 eV; Samson’s points scatter between about 12 and 44 Mb from threshold to about 19 eV (autoionisation structure); above ~20 eV the six sets form one band with a broad maximum near 20-25 eV; Wight’s (e,e) points lie highest, visibly above the photon sets at 20-30 eV; (b) 40-140 eV, a smooth fall, Samson to about 125 eV, de Reilhac lowest above 70 eV.

N2 (Table 3, p. 34, tbl_8d5fc96dd655; Fig. 13, p. 35; stated accuracy better than +-5 %): Denne 1970 (ref. 172; D. R. Denne, J. Phys. D 3, 1392 (1970)), photon, AB, 150-525 eV; Lee 1973 (ref. 208, as for CO), photon, AB, 19-70 eV; Watson 1973 (ref. 254; W. S. Watson, J. Lang and D. T. Stewart, J. Phys. B 6, L148 (1973)), photon, AB, 17-33 eV; Wight 1976 (ref. 256, as for CO), dipole (e,e), TRK, 18-70 eV; de Reilhac 1977 (ref. 170), photon, AB, 24-125 eV; Cole 1978 (ref. 164), photon, AB, 35-250 eV; Samson 1986 (ref. 236, private communication; the table dates it 1986, the same reference’s fragment-ion row 1984), photon, AB, 15-107 eV. Fig. 13: (a) 10-55 eV, threshold line near 15.6 eV; Samson’s points scatter between about 8 and 38 Mb below ~19 eV; above, all sets agree closely, a local maximum near 23 eV and a shoulder near 28 eV, then a smooth fall; (b) 50-250 eV, Cole and Denne to about 250 eV (the axis ends there although Table 3 gives Denne to 525 eV).

O2 (Table 4, p. 40, tbl_812c70798eb7, printed caption ‘Data for O2’, unlabelled in the library extraction; Fig. 18, p. 41; stated accuracy better than +-5 %): Denne 1970 (ref. 172), photon, AB, 150-525 eV; Lee 1973 (ref. 208), photon, AB, 17-70 eV; Watson 1973 (ref. 255; W. S. Watson, J. Lang and D. T. Stewart, Phys. Lett. A 44, 293 (1973)), photon, AB, 20-30 eV; de Reilhac 1977 (ref. 170), photon, AB, 24-124 eV; Cole 1978 (ref. 164), photon, AB, 36-250 eV; Mehlman 1978 (ref. 219; G. Mehlman, D. L. Ederer and E. B. Saloman, J. Chem. Phys. 68, 1862 (1978)), photon, AB, 36-207 eV; Brion 1979 (ref. 149; C. E. Brion, K. H. Tan, M. J. Van Der Wiel and P. E. Van Der Leeuw, J. Electron Spectrosc. Relat. Phenom. 17, 101 (1979)), dipole (e,e), TRK, 5-275 eV; Samson 1984 (ref. 236, private communication), photon, AB, 12-107 eV. Fig. 18: (a) 10-55 eV, threshold line near 12.1 eV; below ~24 eV strong structure (Samson’s points from about 1.5 to 34 Mb); a maximum near 22 eV; above ~25 eV the sets agree, Lee’s and de Reilhac’s points lower at about 25-30 eV; (b) 60-280 eV. The curated weissler_1952 (O2, Table 1, 303.8-1306 A, 9.5-40.8 eV) overlaps panel (a) and is not among the plotted sets.

CO2 (Table 7, p. 62, tbl_714bf2ce3b61; Fig. 37, p. 63; stated accuracy better than +-5 %): Lee 1973 (ref. 208), photon, AB, 17-70 eV; Watson 1975 (ref. 253, as for CO), photon, AB, 19-33 eV; de Reilhac 1977 (ref. 170), photon, AB, 24-125 eV; Hitchcock 1980 (ref. 195; A. P. Hitchcock, C. E. Brion and M. J. Van Der Wiel, Chem. Phys. 45, 461 (1980); author printed ‘Hitchock’ in the table), dipole (e,e), TRK, 8-80 eV (the same row lists its fragment-ion cross sections); Samson 1984 (ref. 236, private communication), photon, AB, 14-107 eV. Fig. 37: (a) 10-45 eV, threshold line near 13.8 eV; Samson’s points from about 12 to 57 Mb below ~19 eV; a maximum of about 36-37 Mb near 21 eV; above, the sets agree, Watson’s points lowest at 21-28 eV; (b) 40-120 eV, de Reilhac’s points scattered on both sides of the others.

N2O (Table 8, p. 69, tbl_6d3c910b76ca; Fig. 43, p. 70; stated accuracy better than +-5 %): Lee 1973 (ref. 208), photon, AB, 17-70 eV; de Reilhac 1977 (ref. 170), photon, AB, 25-120 eV; Cole 1978 (ref. 164), photon, AB, 36-250 eV; Brion 1978 (ref. 147; C. E. Brion and K. H. Tan, Chem. Phys. 34, 141 (1978)), dipole (e,e), NM (normalised at a single energy to a ‘known’ cross section; which one is not stated here), 17-60 eV; Hitchcock 1980 (ref. 195, as for CO2), dipole (e,e), TRK, 8-74 eV. No Samson set. Fig. 43: (a) 10-50 eV, threshold line near 12.9 eV; only Hitchcock’s points below 17 eV; a maximum of about 40 Mb near 19 eV, where Lee’s points scatter between about 31 and 41 Mb; de Reilhac’s single point at 25 eV lies well below the others; Cole’s points lie lowest at 36-50 eV; (b) 50-250 eV, Cole alone above 125 eV.

CH4 (Table 11, p. 89, tbl_5ebdabf5550d; Fig. 60, p. 90; stated accuracy better than +-5 %): Lee 1973 (ref. 208), photon, AB, 19-68 eV; Backx 1975 (ref. 99; C. Backx, G. R. Wight, R. R. Tol and M. J. Van der Wiel, J. Phys. B 8, 3007 (1975)), dipole (e,e) (method printed ‘DIF’, as in the two partial-cross-section rows of ref. 100 and Van der Wiel’s row: a poorly printed ‘DIP’), TRK, 14-80 eV; de Reilhac 1977 (ref. 170), photon, AB, 28-100 eV; Lee 1977 (ref. 209; L. C. Lee, E. Phillips and D. L. Judge, J. Chem. Phys. 67, 1237 (1977)), photon, AB, 17-24 eV; Samson 1984 (ref. 236, private communication), photon, AB, 13-124 eV. Fig. 60: (a) 10-50 eV, threshold line near 12.6 eV; a maximum of about 49 Mb near 14 eV; the sets agree to about 22 eV, but above about 24 eV Lee 1973’s and Backx’s points lie visibly and increasingly above Samson’s, by tens of percent at 30-70 eV (panel b, 50-130 eV, shows the same), while de Reilhac’s points scatter on both sides. This contradicts the stated +-5 % for CH4; the figure does not say which set is right.

SF6 (Table 17, p. 130, tbl_1326a7ba497d; Fig. 95, p. 131; not in the +-5 % list, so ‘better than +-10%’ at most, and the figure shows larger differences): Sasanuma 1971 (reference ‘a’: ‘M. Sasanuma, E. Ishiguro, Y. Moricka, M. Nakamura, III International Conference on Vacuum Ultraviolet Radiation Physics, Tokyo, 1971. Data taken from Lee et al., Ref. 209’, so a reproduction of a reproduction), photon, 15-42 eV; Blechschmidt 1972 (ref. 141; D. Blechschmidt, R. Haensel, E. E. Koch, U. Nielsen and T. Sagawa, Chem. Phys. Lett. 14, 33 (1972)), photon, 15-50 eV; Lee 1977 (ref. 209, as for CH4), photon, 16-65 eV; Hitchcock 1978 (ref. 196; A. P. Hitchcock, C. E. Brion and M. J. Van Der Wiel, J. Phys. B 11, 3245 (1978)), dipole (e,e), TRK, 5-230 eV; Hitchcock 1979 (ref. 197; A. P. Hitchcock and M. J. Van Der Wiel, J. Phys. B 12, 2153 (1979)), dipole (e,e), TRK, 5-63 eV. The photon rows’ normalisation is printed ‘Ab’ in this table (‘AB’ elsewhere). Fig. 95: (a) 0-50 eV, threshold line near 15.7 eV; Sasanuma (labelled ‘*211’ in the legend: ref. 211 is Lucchese and McKoy, Phys. Rev. A 28, 1382 (1983), a calculation on CO, so the legend number is a misprint; the asterisk presumably marks the values as taken from ref. 209) and Blechschmidt drawn as lines, Hitchcock 197 and Lee 209 as points; a peak of about 150 Mb near 23 eV; Blechschmidt’s curve lies far above the others at 16-22 eV (about 100-130 against 70-90 Mb) and below them above about 38 eV, Sasanuma’s above the others at 28-40 eV; (b) 50-250 eV, Hitchcock 197 and Lee 209 to about 70 eV, Hitchcock 196 only at about 160-230 eV (the S 2p inner-shell region with its resonances), nothing between.

H2 (Table 2, p. 30, tbl_cad1ba9400d3; Fig. 10, p. 31; not in the +-5 % list): Cook 1964 (ref. 166; G. R. Cook and P. H. Metzger, J. Opt. Soc. Am. 54, 968 (1964); not the curated metzger_1964, which is O2), photon, AB, 16-22 eV; Denne 1970 (ref. 172), photon, AB, 150-280 eV; Backx 1976 (ref. 138; C. Backx, G. R. Wight and M. J. Van Der Wiel, J. Phys. B 9, 315 (1976)), dipole (e,e), TRK, 10-70 eV; Lee 1976 (ref. 207; L. C. Lee, R. W. Carlson and D. L. Judge, J. Quant. Spectrosc. Radiat. Transfer 16, 873 (1976)), photon, AB, 17-70 eV; Samson 1985 (ref. 236, private communication), photon, AB, 15-124 eV. Fig. 10: (a) 10-45 eV, threshold line near 15.4 eV; Backx’s points highest near threshold (up to about 14 Mb), Samson’s and Cook’s scattered between 0 and 11 Mb below about 17 eV; above ~18 eV all sets agree closely, falling from about 11 Mb near 17 eV; (b) 40-280 eV, Denne’s points near zero at 150-280 eV. D2 is not in the compilation.

O3 is not in the compilation (the 21 molecules are H2, N2, O2, CO, NO, CO2, N2O, H2O, NH3, CH4, HF, HCl, HBr, HI, H2S, CS2, OCS, SO2, SF6, Cl2, CCl4, p. 9), nor are the noble gases.

Partial photoionisation and fragmentation (for later; figures only): electronic partial cross sections, asymmetry parameters and fragment-ion cross sections are in Figs. 11-12 (H2), 14-17 (N2), 19-23 (O2), 25-29 (CO), 38-42 (CO2), 44-48 (N2O), 61-63 (CH4) and 96-103 (SF6), with their sources in the same tables.

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

Datasets

No datasets are recorded.

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.