kligler_1978b ============= D\. J\. Kligler and C\. K\. Rhodes, "Observation of two\-photon excitation of the H2 E,F 1Sigma\_g\+ state", Phys\. Rev\. Lett\. 40, 309\-313 \(1978\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1103/PhysRevLett\.40\.309 `__ **Source kind:** measurement **Recorded technique:** Two\-photon excitation of H2 X 1Sigma\_g\+ \(v = 0\) to the v = 2 level of the inner well of E,F 1Sigma\_g\+ \(about 12\.8 eV\) by an untuned transverse\-discharge ArF\* laser \(Burnham and Djeu's design\)\: about 15 mJ at 193 nm, about 15 ns, full bandwidth about 0\.5 nm, beam 10 mm x 2 mm, focused by a 125 mm Suprasil lens to a 1\.0 x 0\.3 mm spot, peak intensity about 3 x 10^8 W/cm2; H2 from 10 mTorr to 300 Torr, and He/H2 mixtures\. The E,F \-\> B near\-infrared fluorescence \(740\-750 and 820\-830 nm\) collected at f/1 through a long\-pass filter and 10 nm band\-pass filters, detected by an RCA C31034A photomultiplier, averaged over twenty pulses on a Tektronix R7912 transient digitiser; its decay rate against H2 pressure below about 0\.5 Torr \(Fig\. 2\) gives the radiative lifetime \(intercept\) and the quenching rate \(slope\); the absolute fluorescence at high pressure gives an estimate of the two\-photon coefficient \(Eq\. 3\) \(pp\. 310\-312\)\. **Materials in structured entries:** H2 **Dataset quantities:** collisional\_quenching\_rate\_coefficient, radiative\_lifetime **Contents:** 4 datasets; 0 formulas. Curation notes -------------- Phys\. Rev\. Lett\. 40\(5\), 309\-313 \(30 January 1978\) = PDF pages 1\-5 \(journal page = PDF page \+ 308\); a scan with a text layer\. Identity checked on the rendered pages on 2026\-10\-09\: the title, Danield \[sic\] J\. Kligler \(Stanford\) and Charles K\. Rhodes \(SRI International\), received 8 December 1977, on PDF p\. 1 \(journal p\. 309, below the end of the preceding Letter\); headers 'VOLUME 40, NUMBER 5 PHYSICAL REVIEW LETTERS 30 JANUARY 1978'\. This is the Letter that kligler\_1980 \(TC\-1037\) and marinero\_1982 \(TC\-1038\) cite for the E,F lifetime and quenching \(their Ref\. 1 and Refs\. 9\-10\); the id kligler\_1978 is the same group's XeO paper\. Every number below was read on the rendered pages \(pp\. 309\-312\)\. MATERIAL AND LEVEL\. H2 \(normal hydrogen, room temperature; the temperature is not stated\)\. The level is E,F 1Sigma\_g\+ \(v = 2\) of the inner well; with the 0\.5 nm laser band three rotational levels are excited together, 'j = 0 at 103 552 cm^\-1, j = 1 at 103 598 cm^\-1, and j = 2 at 103 682 cm^\-1' \(p\. 311, from Dieke's tables, Ref\. 6\), so the lifetime and rates below are those of the unresolved J = 0\-2 mixture\. TAKEN \(inline text values; no table holds them; p\. 311 and the abstract, p\. 309\)\. radiative\_lifetime \(ns\)\: 'the radiative lifetime of the excited gerade state is 100 \+\- 20 ns' \(tau\_EF\_v2, primary\: this Letter's measurement, the zero\-pressure intercept of Fig\. 2's decay rates\), and 'the theoretical value of 90 ns derived from the theoretical studies of Wolniewicz \[7\] and the Franck\-Condon factors of Spindler \[10\]' \(tau\_EF\_v2\_calc, check\: the Letter does not say who combined the two calculations\)\. collisional\_quenching\_rate\_coefficient \(cm3/s, order 2, channel total\)\: 'the total collisional quenching rate by H2 is \(2\.1 \+\- 0\.4\) x 10^\-9 cm3 sec^\-1' \(kq\_self\_EF, primary, Fig\. 2's slope\) and 'Similar measurements in He/H2 mixtures give the quenching rate by He of \(0\.8 \+\- 0\.4\) x 10^\-9 cm3 sec^\-1' \(kq\_He\_EF, primary\)\. The abstract gives the same three values\. Uncertainty level not stated for any\. Eq\. \(3\) uses k\_q = 2 x 10^\-9 cm3 sec^\-1, the H2 value rounded \(not taken twice\)\. TWO\-PHOTON EXCITATION, NOT TAKEN \(no quantity holds it; as bischel\_1979, TC\-917, and marinero\_1982 decide for the same kind of value\)\. Definition \(p\. 312\)\: Eq\. \(3\), n\* = alpha I^2 / \(hbar omega k\_q\), the steady\-state excited density at high H2 density \(production and collisional quenching both proportional to \[H2\]\), with 'alpha = sigma/I \.\.\. the ratio of the two\-photon absorption cross section sigma \[and\] the laser intensity I'\: the rate per molecule is alpha I^2 / hbar omega\. Measured\: 'alpha ~ 10^\-32 cm4/W', from about 4 x 10^12 photoelectrons/s in the 820\-830 nm band at H2 densities above about 2 x 10^18 cm^\-3 and a laser energy of about 10 mJ, a 0\.15 % detection efficiency, photon flux Phi = 4\.5 x 10^15 sec^\-1, an assumed focal length of 6 mm \(V = 1\.8 x 10^\-3 cm3\), n\* = Phi tau / V = 2\.5 x 10^11 \(with tau = 100 ns\)\. Estimated \(Eqs\. 4\-5, perturbation theory, Ref\. 12\)\: sigma = \[\(2 pi\)^2 / hbar c^2\] I omega \|M\_fg\|^2 g\(omega\), M\_fg = 2 sum\_k \\ / \(E\_kg \- hbar omega\), with one intermediate state \(B 1Sigma\_u\+\), Delta omega\_kg = 45 x 10^3 cm^\-1, mu\_fk^2 = mu\_kg^2 = \(1 D\)^2 and '2 x 10^7 MHz \(effective laser linewidth\) as the proper linewidth factor', giving 'alpha = sigma/I ~ 9 x 10^\-33 cm4/W', 'within 10 %' of the measurement\. Bandwidth\: the ArF\* full bandwidth about 0\.5 nm \(134 cm^\-1 per photon\) spanning the J = 0, 1, 2 lines, so alpha is a band\-averaged peak coefficient for this laser, not a per\-level, frequency\-integrated two\_photon\_excitation\_cross\_section \(cm4\); a conversion needs the line shape and the J populations, an inference\. Photon statistics\: not stated \(a free\-running multimode excimer laser; not corrected\)\. Polarisation\: not stated\. CHECKED \(arithmetic, by hand\)\. n\* = Phi tau / V = 4\.5e15 x 1e\-7 / 1\.8e\-3 = 2\.5e11 cm^\-3 \(printed 'cm3', a misprint for cm^\-3\); V = 0\.6 x 0\.10 x 0\.03 cm^3 = 1\.8e\-3\. The peak intensity\: 15 mJ / 15 ns over 1\.0 x 0\.3 mm is 3\.3e8 W/cm2 \(printed ~3e8\)\. alpha = n\* hbar omega k\_q / I^2 \(Eq\. 3, hbar omega = 1\.03e\-18 J at 193 nm\) is 1\.3e\-32 cm4/W for I = 2e8 W/cm2 \(3e8 scaled to 10 mJ\) and 0\.57e\-32 for 3e8\: the printed ~1e\-32 lies between \(the Letter does not say which I it used\)\. Eq\. \(4\) with the stated inputs in Gaussian units, M\_fg = 2 \(1 D\)^2 / \(h c 45e3 cm^\-1\) and g = 1/\(2e13 s^\-1\), gives 1\.0e\-32 cm4/W \(printed 9e\-33\); with g = 1/\(2 pi 2e13 s^\-1\), 1\.6e\-33\. So the '2 x 10^7 MHz' enters as an angular width, 2e13 s^\-1 = 2 pi x 3\.2e12 Hz \(106 cm^\-1\), the 100 cm^\-1 \(3 x 10^6 MHz\) laser line that bischel\_1979's Table I assumes for its H2 E,F estimate of the same 9 x 10^\-33\. DOUBT\: '4 x 10^12 photoelectrons per second' and '0\.15 % detection efficiency' give 2\.7 x 10^15 photons/s, not the printed Phi = 4\.5 x 10^15 \(a factor 1\.7, unexplained\)\. For scale only \(derived, not taken\)\: sigma\_0 g = alpha hbar omega, so with g = 1/\(2e13 s^\-1\) at the line centre alpha = 1e\-32 cm4/W corresponds to about 2e\-37 cm4 \(angular normalisation\) for the band of three lines\. CHECKED AGAINST THE CITING RECORDS\. kligler\_1980 \(TC\-1037\) holds this Letter's values as reproduced \(tau\_EF\_v2 100 \+\- 20 ns, kq\_self\_EF \(2\.1 \+\- 0\.4\) x 10^\-9, kq\_He\_EF \(0\.8 \+\- 0\.4\) x 10^\-9 cm3/s\) and the calculated 90 ns \(tau\_EF\_v2\_calc\)\: all four agree with the Letter, value and uncertainty; its methods \(decay rate against pressure, slope\) match\. Its 'Ref\. 1 \.\.\. not in the library' is now this record\. marinero\_1982 quotes 100 \+\- 20 ns\: agrees\. bischel\_1979 \(TC\-917\) quotes the measured 'alpha ~ 10^\-32 cm4/W' \(its p\. 385\)\: agrees\. kligler\_1980's Fig\. 3 level energies of E,F \(v = 2\) J = 0, 1, 2 \(103 552, 103 598, 103 682 cm^\-1\) equal this Letter's\. NOT TAKEN \(no quantity, or not a curated material\)\. The E,F \(v = 2\) J = 0, 1, 2 level energies \(molecular\_level\_energy declined, TC\-1040; Dieke's tables\); the D2 and HD E,F \(v = 2\) levels '~102 740 cm^\-1' and '~103 220 cm^\-1' \(not optmat materials\); the \(830 nm\)/\(750 nm\) band intensity ratio 1\.4 \+\- 0\.2 against Wolniewicz's A\_2,1/A\_2,0 = 1\.51 \(p\. 311; a ratio of bands, no quantity\); the two\-photon range '~103 350 and ~103 681 cm^\-1' covered by the 0\.5 nm band; Fig\. 2's decay rates \(a raster scan of the measurements whose fitted intercept and slope the text prints; rule 8\); Fig\. 1 \(a potential\-curve diagram after Sharp\)\. No excited\-state photoionisation cross section and no ionisation are reported\. FURTHER DATA CITED, NOT IN THE LIBRARY \(checked by folder name\)\: L\. Wolniewicz, J\. Chem\. Phys\. 51, 5002 \(1969\) \(Ref\. 7, E,F \-\> B transition moments\); R\. J\. Spindler, J\. Quant\. Spectrosc\. Radiat\. Transfer 9, 1041 \(1969\) \(Ref\. 10\); W\. K\. Bischel, P\. J\. Kelley and C\. K\. Rhodes, Phys\. Rev\. A 13, 1829 \(1976\) \(Ref\. 12, two\-photon perturbation theory and line\-shape factors\); I\. Dabrowski and G\. Herzberg, Can\. J\. Phys\. 54, 525 \(1976\) \(Ref\. 9, HD E,F levels\)\. **Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- kligler\_1978b/tau\_EF\_v2 ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "tau_EF_v2", "material": "H2", "table": "text", "quantity": "radiative_lifetime", "unit": "ns", "abscissa": "label", "use": "primary", "parameters": { "method": "measured: decay rate of the E,F -> B fluorescence after two-photon ArF* excitation against H2 pressure (0-500 mTorr, Fig. 2), zero-pressure intercept" }, "uncertainty": { "column": true, "level": "not stated" } } 1 inline points in the source record. p\. 311\: 'Measurements of fluorescence decay rate below ~0\.5 Torr are shown in Fig\. 2\. These data indicate that the radiative lifetime of the excited gerade state is 100 \+\- 20 ns'; also the abstract \(p\. 309\)\. The zero\-pressure intercept of the decay rate of the E,F \-\> B fluorescence against H2 pressure \(0\-500 mTorr\)\. kligler\_1980's tau\_EF\_v2 reproduces it\. Level of the uncertainty not stated\. kligler\_1978b/tau\_EF\_v2\_calc ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "tau_EF_v2_calc", "material": "H2", "table": "text", "quantity": "radiative_lifetime", "unit": "ns", "abscissa": "label", "use": "check", "parameters": { "method": "calculated from Wolniewicz's E,F -> B transition moments (J. Chem. Phys. 51, 5002 (1969)) and Spindler's Franck-Condon factors (J. Quant. Spectrosc. Radiat. Transfer 9, 1041 (1969)), as cited" } } 1 inline points in the source record. p\. 311\: 'This radiative lifetime is in excellent agreement with the theoretical value of 90 ns derived from the theoretical studies of Wolniewicz \[7\] and the Franck\-Condon factors of Spindler \[10\]\.' Wolniewicz's E,F \-\> B transition moments and Spindler's Franck\-Condon factors, combined by an unnamed hand \(the Letter does not say whether by the authors\); check, not either source's own value\. No uncertainty\. kligler\_1978b/kq\_self\_EF ~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "kq_self_EF", "material": "H2", "table": "text", "quantity": "collisional_quenching_rate_coefficient", "unit": "cm3/s", "scale": 1e-09, "abscissa": "label", "use": "primary", "parameters": { "perturber": "self", "order": 2, "channel": "total", "method": "time-resolved E,F -> B fluorescence against H2 pressure (0-500 mTorr, Fig. 2), slope" }, "uncertainty": { "column": true, "level": "not stated" } } 1 inline points in the source record. p\. 311\: 'the total collisional quenching rate by H2 is \(2\.1 \+\- 0\.4\) x 10^\-9 cm3 sec^\-1'; also the abstract\. The slope of Fig\. 2's decay rate against H2 pressure; the pressure\-to\-density conversion and the temperature are not stated \(room temperature\)\. The Letter expects rotational relaxation and transfer to C 1Pi\_u \(its reaction 2\) to dominate\. kligler\_1980's kq\_self\_EF reproduces it\. Level of the uncertainty not stated\. kligler\_1978b/kq\_He\_EF ~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "kq_He_EF", "material": "H2", "table": "text", "quantity": "collisional_quenching_rate_coefficient", "unit": "cm3/s", "scale": 1e-09, "abscissa": "label", "use": "primary", "parameters": { "perturber": "He", "order": 2, "channel": "total", "method": "time-resolved E,F -> B fluorescence in He/H2 mixtures against He pressure" }, "uncertainty": { "column": true, "level": "not stated" } } 1 inline points in the source record. p\. 311\: 'Similar measurements in He/H2 mixtures give the quenching rate by He of \(0\.8 \+\- 0\.4\) x 10^\-9 cm3 sec^\-1'; also the abstract\. The mixtures' composition and pressures and the temperature are not stated\. kligler\_1980's kq\_He\_EF reproduces it\. Level of the uncertainty not stated\. 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.