walsh_1993 ========== T\. D\. G\. Walsh, J\. E\. Decker and S\. L\. Chin, "Tunnel ionization of simple molecules by an intense CO2 laser", J\. Phys\. B\: At\. Mol\. Opt\. Phys\. 26, L85 \(1993\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1088/0953\-4075/26/4/002 `__ **Source kind:** measurement **Recorded technique:** Ion yields against intensity for Xe, Kr, Ar, Ne, He and the molecules O2, CO, NO and CO2 \(with N2 and H2 in the figure\) in the field of a nanosecond CO2 laser \(the wavelength is not stated\), focused by an f/1 on\-axis parabolic copper mirror \(50 mm focal length\); ions by time of flight\. The intensity scale is set by xenon\: 'the value for the experimental saturation intensity was set equal to the calculated value and the other gases were scaled accordingly' \(p\. 3\)\. Saturation intensities read from the log\-log yield curves \(intersection of the unsaturated slope with a 3/2\-slope tangent\) are compared with the Ilkov\-modified ADK rate \(pp\. 3\-4\)\. **Materials in structured entries:** Xe **Dataset quantities:** None recorded. **Contents:** 0 datasets; 1 formula. Curation notes -------------- Pages are pdf pages\: pdf page 1 is the IOPscience download cover, so pdf pp\. 2\-7 are journal pp\. L85\-L90\. Identity checked against pdf p\. 2\. WHY NOTHING IS TAKEN\. The saturation intensities are in Fig\. 1 only \(p\. 4\: 'Experimental saturation intensities as a function of ionization potential for different atomic and molecular species', with the curve from Eqs\. \(1\)\-\(2\)\)\: Xe\+, Kr\+, Ar\+ \('Ne\+ and He\+ did not show saturation in the range of our laser intensity', p\. 4\), N2\+ and H2\+ \(whose atom\-like behaviour the text attributes to Chin et al\. 1992, J\. Phys\. B 25, L249, not saying whether the points are new\), O2\+, CO\+, NO\+ and CO2\+ \(from the summed CO2 spectrum, Fig\. 3\)\. Fig\. 2 \(p\. 5\)\: yields of CO\+, O\+, C\+ and CO2\+ from CO2, with Xe\+ as the intensity reference; Fig\. 3 \(p\. 6\)\: their sum\. No number is printed for any saturation intensity, and every intensity is relative to xenon's calculated one\. VALUES IN THE TEXT \(p\. 5, uncited, used to argue the fragmentation sequence; not taken\)\: ionisation potentials O 13\.62 eV, CO 14\.01 eV, C 11\.3 eV, Xe 'E0\(Xe\) = 12\.13'\. Their kind \(adiabatic or vertical\) is not stated; the CO value, the only molecule in scope, is a reprint of an unstated source\. CONCLUSION \(p\. 7\)\: 'in the absence of ground\-state vibrational resonance, simple molecules \(diatomic and triatomic\) would tunnel ionize as if they were structureless atoms having ionization potentials equal to those of the ground\-state molecules'\. The formula below is the one saenz\_2002 uses for its ADK rows \('Eq\. \(1\) of Ref\. \[7\]'\)\. **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 -------- walsh\_1993/adk\_ilkov ~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "adk_ilkov", "material": "Xe", "equation": "Eq. (1), p. 3", "printed": "w = (3e/pi)^(3/2) Z^2 (2l + 1)/(3 (2n* - 1) n*^3) (4e Z^3/((2n* - 1) n*^3 F))^(2n* - 3/2) exp(-2 Z^3/(3 n*^3 F))", "variable": "e = 2.718...; Z: the ionic charge; l: the orbital angular momentum quantum number; F: the laser field strength; n* = Z/sqrt(2 E0), E0 the ionisation potential (atomic units implied, not stated)", "range": "The tunnelling regime (not stated further); Eq. (2) defines the saturation intensity I_s by p = int w(I = I_s) dt = 1", "coefficients": {}, "reproduced_from": [ "ilkov_1992" ], "check": "Checked against the equation image (eq_d0800f17dc00.jpg). Identical term by term to the original, ilkov_1992 Eq. (7) (formula eq7_ground_state; checked on its page image, p. 4008). Not checkable against printed rates (none). Compared (computed 2026-09-26) with the cycle-averaged ADK rate with m = 0 and the Stirling C_n*l^2 = (2e/n*)^(2n*)/(2 pi n*) (augst_1991 Eqs. (8)-(10)): the field dependence is identical, since 2Z^3/(3 n*^3 F) = 2(2E0)^(3/2)/(3F), and the ratio is a constant depending on n*: 0.943 for Xe (E0 = 12.13 eV, l = 1), 1.063 for E0 = 15.43 eV and 1.309 for E0 = 24.587 eV (l = 0)." } 'The tunnel ionization rate obeys the following modified \(Ilkov et al 1992\) equation' \(p\. 3\)\: one electron, m = 0 \(no m dependence\), no occupancy factor; the material is nominal \(the paper applies it to all its atoms and molecules\)\. 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.