bischel_1979 ============ W\. K\. Bischel, J\. Bokor, D\. J\. Kligler and C\. K\. Rhodes, "Nonlinear optical processes in atoms and molecules using rare\-gas halide lasers", IEEE J\. Quantum Electron\. QE\-15, 380\-392 \(1979\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1109/jqe\.1979\.1070000 `__ **Source kind:** theory **Recorded technique:** A review of the authors' experiments with ArF \(193 nm\) and KrF \(248 nm\) lasers \(two\-photon excitation of H2 E,F, Kr 4p5 6p and Xe 5p5 6p; Xe\+ by two\-photon ionisation; XeF\*, XeO\*, KrO\*; OCS photolysis\), with estimates of two\-photon absorption coefficients from second\-order perturbation theory \(Sec\. II, Eqs\. 1\-3, Table I\)\: one intermediate state, transition moments mu\_1^2 and mu\_2^2 of order 1 debye^2, an energy denominator, and a Gaussian laser line of 100 cm^\-1 for the bound transitions \(Ref\. 18's \(2 Delta^2 \+ Delta nu\_D^2\)^1/2 replacing the Doppler width\)\. **Materials in structured entries:** Xe **Dataset quantities:** multiphoton\_ionization\_cross\_section **Contents:** 1 dataset; 0 formulas. Curation notes -------------- Journal pp\. 380\-392 = PDF pages 1\-13 \(a scan with a text layer\)\. Identity checked on the first page \(IEEE Journal of Quantum Electronics, vol\. QE\-15, no\. 5, May 1979, p\. 380; W\. K\. Bischel, J\. Bokor, D\. J\. Kligler and C\. K\. Rhodes; manuscript received November 1, 1978, revised January 16, 1979\) on 2026\-10\-09\. THE DEFINITION \(p\. 381, Eq\. 1; p\. 382\), quoted\: 'the two\-photon absorption cross section for light at frequency nu\_2 with intensity I\_2 induced by light at frequency nu\_1 with intensity I\_1 is given by sigma\(nu\_2\) = alpha I\_1 = \(2 pi\)^3 / \(h c^2\) nu\_2 \|M\_fg\|^2 g\(nu\_1, nu\_2\) I\_1' \(Eq\. 1\), and the rate equation \(4\) uses 'W\_fg = alpha I^2 / hbar omega' \(p\. 382\)\: alpha in cm^4/watt is the transition rate per atom times hbar omega / I^2, the definition mccown\_1982 \(its Eq\. 9, TC\-884\) and hodges\_1981 \(its Eq\. 1, which cites this paper\) use\. The generalised cross section on the photon flux is sigma\_2 = alpha hbar omega \(1\.03e\-52 cm4 s for alpha = 1e\-34 at 193 nm; not printed\)\. For the ionisation row the 'Line Width' entering g is not the laser's\: footnote \(g\), '~10^9 MHz', 'Estimated for photoionization continuum' \(about 3 x 10^4 cm^\-1\), against footnote \(a\)'s 'Estimated laser linewidth' of 3 x 10^6 MHz \(100 cm^\-1\) for the bound rows\. The paper prints the inputs but not Eq\. \(1\)'s polarisation factors or units; the estimates are not reproduced here\. THE XENON ESTIMATE \(Table I, p\. 381\)\: Xe, 193 nm, excited product Xe\+, energy denominator 16 x 10^3 cm^\-1, line width ~10^9 MHz \(g\), mu\_1^2 = mu\_2^2 = 1 debye^2, alpha = 1 x 10^\-34 cm4/watt\. The text \(p\. 386\)\: at 193 nm 'the two\-photon linewidth covers the region from 103 300\-103 560 cm^\-1', between the Xe\+ 2P3/2 and 2P1/2 limits \(Fig\. 4\), and 'Because autoionizing states are observed in the linear ionization spectrum \[40\] in both the ns and nd channels, it is likely that similar np and nf channels will influence the two\-photon amplitude\. These resonances could enhance the value of alpha given in Table I by a factor of ~10^2\.' Repeated on p\. 388\: 'sigma / I ~ 10^\-34 cm4/W \(see Table I\)'; with 'an Xe density ~3 x 10^17 cm^\-3 and an optical intensity of 10^9 W/cm^2' it gives 'an estimated ion density of ~3 x 10^11 cm^\-3' \(the laser pulse 20 ns\)\: the definition above gives 5\.8e11, twice the printed value \(2\.9e11 for a 10 ns pulse\); an order\-of\-magnitude estimate\. The authors observed Xe\+ \(828 nm recombination line, Xe2\* emission at 172 nm, Fig\. 5\) but measured no coefficient\: 'an accurate measurement of the two\-photon ionization cross section could make this an important alternate technique' \(p\. 388\)\. QUOTED ELSEWHERE, CHECKED\. mccown\_1982 \(TC\-884\) holds '1 x 10^\-34' as Bischel et al\.'s \(Table I there, Ref\. 11\)\: the value matches \(the script checks it\)\. FINDING\: mccown\_1982 describes it as an estimate 'assuming a laser linewidth of 100 cm\-1' \(its p\. 3322, from this paper's p\. 381\); this paper's Table I gives the Xe\+ row the continuum width of footnote \(g\), ~10^9 MHz, not the 100 cm\-1 \(3 x 10^6 MHz\) of the bound rows\. The factor ~10^2 for autoionising resonances that McCown et al\. and hodges\_1981 quote matches p\. 386\. hodges\_1981 quotes '1 x 10^\-34 cm4 W\-1'\: matches\. KRYPTON \(OEP 6, Q2\)\. The paper has no krypton two\-photon ionisation cross section \(table, vector figure or raster figure\)\. Table I's Kr row is a bound two\-photon excitation estimate\: 193 nm, Kr\* 4p5 6p, energy denominator 30 x 10^3 cm^\-1, 100 cm^\-1 laser line \(3 x 10^6 MHz\), alpha = 1 x 10^\-31 cm4/watt; the experiment \(pp\. 386\-387\) excites 4p5 6p\(1 1/2\)2 'at 103 363 cm^\-1' and estimates an excited density \> 1\.5 x 10^13 cm^\-3 from the fluorescence\. geohegan\_1986 \(TC\-886\) quotes '\(1\-2\.3\) x 10^\-31 cm^4 W^\-1' for this transition from Bokor and co\-workers and Bischel et al\. 'assuming a 100\-cm\-1\-bandwidth ArF laser'\: this paper's 1 x 10^\-31 is the lower end, for 100 cm^\-1; the 2\.3 x 10^\-31 is not in this paper \(the bokor\_1980 record gives 2\.34 x 10^\-31 for that paper's 25 cm^\-1 laser\)\. DOUBT\: Table I prints the Kr level at '103,762 cm^\-1', the text \(p\. 386\) at '103 363 cm^\-1'; only the latter lies inside the ArF two\-photon range the paper gives \(103 300\-103 560 cm^\-1, p\. 386\)\: probably a misprint in Table I \(no value of it is taken\)\. NOT TAKEN \(no quantity of the vocabulary holds them\)\: Table I's bound two\-photon excitation estimates of alpha \(cm4/watt; H2 E,F 9 x 10^\-33, CO F 5 x 10^\-33, N2 E 4 x 10^\-34, Kr 4p5 6p 1 x 10^\-31, I2 6 x 10^\-31 at 193 nm; Xe 5p5 6p 8 x 10^\-32 and N2O ~3 x 10^\-35 at 248 nm\)\: linewidth\-dependent peak coefficients, not the frequency\-integrated two\_photon\_excitation\_cross\_section \(a conversion would need the assumed line shape, an inference\); the H2 measurement 'alpha ~ 10^\-32 cm4/W' for E,F \(v = 2\) \(p\. 385\); the N2O upper limit 'alpha \< 3 x 10^\-34 cm4/W' \(p\. 388; not a curated material\); Table II \(H2, HD, D2 two\-photon transition ranges and emission wavelengths\), Table III \(H2 E,F \-\> B line intensities\); the quenching rates and cross sections \(pp\. 383\-389\)\. Further two\-photon data the paper cites\: D\. J\. Kligler and C\. K\. Rhodes, Phys\. Rev\. Lett\. 40, 309 \(1978\) \(H2 E,F two\-photon excitation, Ref\. 1\), held as kligler\_1978b \(TC\-1043\); D\. Kligler, D\. Pritchard, W\. K\. Bischel and C\. K\. Rhodes, J\. Appl\. Phys\. 49, 2219 \(1978\) \(Xe two\-photon excitation at 248 nm, Ref\. 10\), held as kligler\_1978 \(TC\-1021\)\. Not in the library\: B\. R\. Marx, J\. Simons and L\. Allen, J\. Phys\. B 11, L273 \(1978\) \(the line\-shape factor, Ref\. 18\)\. **Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- bischel\_1979/alpha\_Xe ~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "alpha_Xe", "material": "Xe", "file": "Xe/bischel_1979__alpha_Xe.csv", "table": "tbl_246cdac4e41d", "quantity": "multiphoton_ionization_cross_section", "unit": "cm4 W-1", "scale": 1e-34, "abscissa_unit": "nm", "use": "check", "uncertainty": { "level": "not stated" }, "parameters": { "photons": 2, "polarization": "not stated", "method": "estimate from second-order perturbation theory with one intermediate state (Eqs. 1-3): energy denominator 16 x 10^3 cm^-1, mu_1^2 = mu_2^2 = 1 debye^2, line width ~10^9 MHz 'estimated for photoionization continuum'", "definition": "sigma(nu_2) = alpha I_1 (Eq. 1, p. 381) and W_fg = alpha I^2 / hbar omega (p. 382); alpha in cm^4/watt", "wavelength_nm": 193, "linewidth_mhz": 1000000000.0, "linewidth_definition": "'~10^9 (g)', footnote (g): 'Estimated for photoionization continuum' (Table I)", "energy_denominator_cm1": 16000 } } Table I \(p\. 381\), xenon, 193 nm, excited product Xe\+\: the estimated coefficient alpha in cm4/watt \(rate alpha I^2 / hbar omega; sigma\_2 = alpha hbar omega = 1\.03e\-52 cm4 s\), for the photoionisation continuum \(line width ~10^9 MHz, footnote g\), without the autoionising resonances, which 'could enhance the value of alpha given in Table I by a factor of ~10^2' \(p\. 386\)\. One significant figure; an order\-of\-magnitude estimate\. 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 :doc:`review register ` for the checks and decisions.