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 · Catalogue · 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 <f|e1.mu|k><k|e2.mu|g> / (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#
{
"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#
{
"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#
{
"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#
{
"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 review register for the checks and decisions.