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 · Catalogue · Review register
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 review register for the checks and decisions.