tunnermann_1992 =============== A\. Tünnermann, K\. Mossavi and B\. Wellegehausen, "Nonlinear\-optical processes in the near\-resonant two\-photon excitation of xenon by femtosecond KrF\-excimer\-laser pulses", Phys\. Rev\. A 46, 2707 \(1992\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1103/PhysRevA\.46\.2707 `__ **Source kind:** measurement **Recorded technique:** A femtosecond KrF system \(Szatmari and Schäfer\)\: 248\.5 nm, 10 mJ, 360 fs, linearly polarised, bandwidth about 100 cm^\-1 \(time\-bandwidth product 1\.23\), focused by f = 1000 mm to a 50 um spot \(confocal parameter 16 mm\), up to 10^15 W/cm2, into a xenon cell with LiF windows at 0\.05\-760 Torr\. Emission analysed forward, backward and sideways from 115 to 1200 nm \(monochromators, calibrated pyroelectric meters, streak camera, autocorrelators, CCD\)\. The difference\-frequency susceptibilities are inferred from the four\-wave parametric gain \(Eqs\. 4\-6\) with an assumed average pump intensity; the calculation is a stationary four\-level model \(pp\. 2708, 2715\-2716\)\. **Materials in structured entries:** None recorded. **Dataset quantities:** None recorded. **Contents:** 0 datasets; 0 formulas. Curation notes -------------- No datasets\. Identity checked on the first page\: Tünnermann, Mossavi and Wellegehausen, Phys\. Rev\. A 46 \(No\. 5, 1 September 1992\), 2707\-2717; PDF pages 1\-11 = journal pp\. 2707\-2717, PDF pages 12\-13 repeat Figs\. 1 and 13\. It is Ref\. \[6\] of lehmberg\_1995 \(the 6p\[1/2\]0 resonance used at high KrF intensity\)\. WHAT IT REPORTS\. Near\-resonant two\-photon excitation of Xe 6p\[1/2\]0 and 6p\[3/2\]2 by 248\.5 nm light, detuned by 'Delta E = 363 cm^\-1' and '1270 cm^\-1' \(p\. 2708; Fig\. 6 marks 2 hbar w at 80483 cm^\-1\)\. Checked against NIST \(TC\-983 levels\)\: 2/248\.5 nm \- 80118\.962 = 363\.9 cm^\-1 and \- 79212\.465 = 1270\.4 cm^\-1, so 248\.5 nm is the vacuum wavelength; the 828\.01 and 823\.16 nm of Fig\. 6 are air wavelengths \(NIST 823\.3897 nm vacuum\)\. The sideways 828 nm fluorescence grows as the square of the pump \(Fig\. 7, 'Slope ~ 2' at low intensity, saturating above\)\: two\-photon population\. ASE and stimulated hyper\-Raman emission on 6p\[1/2\]0 \-\> 6s\[3/2\]1 \(828 nm\) and 6p\[3/2\]2 \-\> 6s\[3/2\]2 \(823 nm\); the 823/828 fluorescence ratio 'corresponds well to the oscillator strengths' of Aymar and Coulombe \(no values printed, so nothing to compare with NIST\)\. Four\-wave parametric oscillation 2 w\_p = w\_vis \+ w\_vuv \(650\-850 nm with 147\-155 nm\) and in the uv \(185\-400 nm\), up to 100 MW; 828 nm output 45 uJ at 760 Torr \(p\. 2709\); visible continuum 600 fs autocorrelation, 60 uJ at 45 Torr; vuv over 30 uJ at 40 Torr\. LEVEL SHIFTS\. The authors attribute the resonant emission to a ponderomotive shift of the 6p \(and 6s\) levels, U\_p = e^2 I/\(2 eps0 mu w^2 c\) \(Eq\. 1, p\. 2710\)\: 8 x 10^12 W/cm2 closes 363 cm^\-1 and 3 x 10^13 W/cm2 closes 1270 cm^\-1\. SUSCEPTIBILITIES\. With the parametric gain G0^2 = 9 w\_vis w\_vuv \|chi\(3\)\|^2 N^2 I\_p^2 / \[\(2 c^2 eps0\)^2 n\_vis n\_vuv n\_p^2\] \(Eq\. 5, SI, after Hanna, Yuratich and Cotter\) and 'an average value of 10^14 W/cm2' for I\_p, the microscopic difference\-frequency susceptibility is '\|chi\(3\)\(280 nm\)\| = 5 x 10^\-51 m^5/V^2' and, with an absorption of 0\.08 cm^\-1 \(Castex\), '\|chi\(3\)\(148\.5 nm\)\| = 10^\-48 m^5/V^2', the latter enhanced by the 6s\[3/2\]1 resonance at 146\.9 nm \(p\. 2715\); the abstract gives 10^\-48 to 10^\-50 m^5/V^2\. Fig\. 19 \(raster\) draws the calculated \|chi\(3\)\| of w\_vuv = 2 w\_p \- w\_vis from 130 to 200 nm, plotted 'x0\.25', with the measured rhombs\: a four\-level model \(5p6, 6s\[3/2\]1, 6s'\[1/2\]1, 6p\[1/2\]0\), Aymar and Coulombe's oscillator strengths, no damping, saturation or level shift \(pp\. 2715\-2716\)\. NOT TAKEN \(awaiting vocabulary\)\: the two \|chi\(3\)\| values and Fig\. 19\. nonlinear\_susceptibility would hold them \(process 'other', part 'electronic'\), but no entry of CONVENTIONS is Hanna, Yuratich and Cotter's per\-atom SI chi\(3\) \(a candidate quantity, not yet in the vocabulary\)\. They are magnitudes inferred from a gain at an assumed intensity, good to about an order of magnitude\. NOT TAKEN \(reproduced, no quantity\)\: 'two\-photon absorption cross sections around 10^\-36 cm^4/W', quoted from Kligler et al\. \(Ref\. \[32\]\) for the detuned levels \(p\. 2708\), a coefficient in cm4/W, not sigma\_0^\(2\)\. DOUBTS\. \(1\) p\. 2715 says Fig\. 19 was calculated 'for a fixed pump\-laser detuning of 0\.2 nm from the 6p\[1/2\]0 two\-photon resonance'; 363 cm^\-1 is 1\.12 nm of pump wavelength \(0\.2 nm would be 65 cm^\-1 in 2w\), and tunnermann\_1993 states 363 cm^\-1 for the same calculation\. \(2\) tunnermann\_1993 says the FWPO values are at 148\.5 and 320 nm, this paper at 148\.5 and 280 nm\. \(3\) 'The xenon molecules concentration at room temperature amounts to 0\.5 % of the atomic density', 'about 10^15 cm^\-3' at 30 Torr \(p\. 2714\)\: 0\.5 % of 9\.7 x 10^17 cm^\-3 is 4\.8 x 10^15, and the dimer fraction grows with pressure \(lehmberg\_1995\: about 0\.6 % at 1 atm\), so the two statements disagree\. TWO\-PHOTON STRENGTH\. Nothing here implies a 6p\[1/2\]0 strength\: \|chi\(3\)\| is the magnitude of a nondegenerate susceptibility at an assumed intensity, and its resonant part multiplies the two\-photon amplitude by a different \(w\_vis, w\_vuv\) amplitude whose oscillator strengths are not printed\. Krypton appears only as a proposal \(216 or 193 nm excitation, p\. 2716\)\. Register\: TC\-998\. **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 :doc:`review register ` for the checks and decisions.