trickl_1989#
T. Trickl, E. F. Cromwell, Y. T. Lee and A. H. Kung, “State-selective ionization of nitrogen in the X 2Sigma_g+ v+ = 0 and v+ = 1 states by two-color (1+1) photon excitation near threshold”, J. Chem. Phys. 91, 6006 (1989)
Source record · Catalogue · Review register
DOI: 10.1063/1.457417
Source kind: measurement
Recorded technique: Two-colour (1+1) resonance-enhanced photoionisation of N2 in a pulsed, collimated jet (estimated density 1e13 cm^-3): XUV light (frequency-tripled, pulse-amplified cw ring dye laser, bandwidth slightly above 210 MHz) excites the c4’ 1Sigma_u+ (v’ = 0, 1) Rydberg states from X 1Sigma_g+ (v’’ = 0), and a second pulsed dye laser (Coumarin 460, bandwidth 0.5 cm^-1, <= 1 mJ) is scanned across the N2+ X 2Sigma_g+ v+ = 0 and v+ = 1 thresholds; ions extracted by a delayed 23.6 V/cm pulse (field-free ionisation), mass-selected by time of flight. Laser 1 calibrated with the Autoscan wavemeter against I2 lines; laser 2 against a neon reference spectrum (pp. 6006-6007, 6009).
Materials in structured entries: N2
Dataset quantities: ionization_energy
Contents: 3 datasets; 0 formulas.
Curation notes#
PDF pages 2-8 = journal pages 6006-6012 (PDF page 1 is the publisher’s cover sheet). Identity checked on the first page. Nitrogen only.
THE IONISATION ENERGY (p. 6010, and the abstract, p. 6006): ‘The resulting ionization energy of N2 is 125 666.959(67) cm^-1.’ It is the sum of the c4’ <- X (0,0) R0 line of Table I (104 326.451(25) cm^-1, from X (v’’ = 0, J’’ = 0) to c4’ (v’ = 0, J’ = 1)) and the limit of the nd delta_g 1Delta_g Rydberg series excited from c4’ (0, J’ = 1), nu_inf = 21 378.952(22) cm^-1 (’+-0.060 cm^-1, if one includes the calibration error’; Eq. (2), 50 <= n <= 74, Table II), less the rotational energy of the N+ = 4 level to which the series converges (the N+ = 4 threshold computed from the literature, Refs. 30 and 31, and Table I, is 21 378.793 cm^-1). It is therefore the energy from the neutral’s rotationless level X 1Sigma_g+ (v = 0, J = 0) to the ion’s rotationless level X 2Sigma_g+ (v+ = 0, N+ = 0); the ion’s spin-doublet splitting ‘is very small and cannot be resolved in our experiment’ (p. 6009). Check (not printed): 104 326.451 + 21 378.952 = 125 705.403 cm^-1, and 125 705.403 - 125 666.959 = 38.444 cm^-1 is the N+ = 4 rotational energy the paper subtracted (N(N+1) B+ = 20 B+ with B+ = 1.922 cm^-1). The uncertainty (67) is stated without a confidence level; it is close to the series limit’s 0.060 cm^-1 with the calibration error, combined with the R0 line’s 0.025 cm^-1.
A SECOND DETERMINATION (p. 6008): the field-dependent threshold of the ion signal from c4’ (0, J’ = 1), fitted by nu_thr(E) = 21 340.54(56) cm^-1 - 5.55 sqrt(E [V/cm]) (Eq. (1), E <= 100 V/cm, thresholds at half-rise), plus the R0 line: ‘an ionization energy for N2 of 125 666.99(56) cm^-1 which is close to the value given by Ogawa and Tanaka of 125 666.8 cm^-1’, taken to correspond to ions in N+ = 0 (the N+ = 1 and 2 levels are 3.84 and 11.53 cm^-1 higher). Recorded as a check value, superseded within the paper by the series limit.
v+ = 1: the paper gives no ionisation energy to X 2Sigma_g+ v+ = 1. The spectrum of Fig. 2(d) (from c4’ (v’ = 1, J’ = 1), laser 2 near 465.7 nm) ‘could not be analyzed because of the lower resolution chosen for this scan’ (p. 6011).
In eV (not printed; hc = 1.239841984e-4 eV cm): 125 666.959 cm^-1 = 15.580717 eV (+-8.3e-6 eV); 125 666.99 cm^-1 = 15.58072 eV.
NOT EXTRACTED (notes only): - Table I (p. 6007): N2 transition frequencies (cm^-1) measured in single-laser (1+1) ionisation: c4’ <- X (0,0) R0-R2 104 326.451(25), 104 330.190(25), 104 333.802(25); c4’ <- X (1,0) R0, R1 106 372.005(35), 106 374.849(35); c3 <- X (0,0) R0-R2, Q1, Q2; b’ <- X (2,0) R0-R2; with the lines computed from the literature (Carroll et al., Lofthus, Proch & Trickl, Bendtsen, Vanderslice et al.). XUV transition frequencies, not ionisation data. - Table II (p. 6011): 25 measured nd delta_g Rydberg lines (n = 50-74, 21 335.260 to 21 358.923 cm^-1) from c4’ (0) J’ = 1, with Eq. (2)’s values (R = 109 735.17 cm^-1, mass-corrected) and the differences (within +-0.11 cm^-1); fitted delta = -0.088(22). - The J’ = 2 and 3 series (Figs. 2(b), 2(c)) converge to N+ = 5 and 6 after a 0.73 cm^-1 correction attributed to a calibration change of laser 2 or a Stark shift (p. 6011); quantum defects -0.18. - Other energies quoted: the N2+ A 2Pi_u threshold 9016.021(8) cm^-1 above the X threshold (Benesch et al., p. 6007); omega_e of N2+ X 2207.0366 +- 0.05 cm^-1 (Gottscho et al., p. 6010).
Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.
Datasets#
trickl_1989/ie_N2#
{
"id": "ie_N2",
"material": "N2",
"table": "text",
"quantity": "ionization_energy",
"unit": "cm-1",
"abscissa": "label",
"use": "primary",
"parameters": {
"kind": "adiabatic",
"final_state": "X 2Sigma_g+ (v+ = 0, N+ = 0)",
"initial_state": "X 1Sigma_g+ (v = 0, J = 0)"
},
"uncertainty": {
"column": true,
"level": "not stated"
}
}
1 inline points in the source record.
p. 6010 (and abstract, p. 6006): ‘The resulting ionization energy of N2 is 125 666.959(67) cm^-1’, from the Rydberg series limit converging to N+ = 4, reduced to N+ = 0 with the literature rotational energy (record notes). = 15.580717 eV. The confidence level of (67) is not stated.
trickl_1989/threshold_N2#
{
"id": "threshold_N2",
"material": "N2",
"table": "text",
"quantity": "ionization_energy",
"unit": "cm-1",
"abscissa": "label",
"use": "check",
"parameters": {
"kind": "adiabatic",
"final_state": "X 2Sigma_g+ (v+ = 0, N+ = 0)",
"initial_state": "X 1Sigma_g+ (v = 0, J = 0)"
},
"uncertainty": {
"column": true,
"level": "not stated"
}
}
1 inline points in the source record.
p. 6008: the zero-field extrapolation of the ion-signal threshold (Eq. (1), half-rise, E <= 100 V/cm) plus the c4’ <- X (0,0) R0 line, ‘an ionization energy for N2 of 125 666.99(56) cm^-1’, which ‘corresponds to ions in the N+ = 0 rotational level’. The paper’s less precise determination, superseded by ie_N2: a check.
trickl_1989/ogawa_1962_N2#
{
"id": "ogawa_1962_N2",
"material": "N2",
"table": "text",
"quantity": "ionization_energy",
"unit": "cm-1",
"abscissa": "label",
"use": "reproduced",
"reproduced_from": [
"M. Ogawa and Y. Tanaka, Can. J. Phys. 40, 1593 (1962)"
],
"parameters": {
"kind": "adiabatic",
"final_state": "X 2Sigma_g+ (v+ = 0)"
}
}
1 inline points in the source record.
p. 6008: ‘the value given by Ogawa and Tanaka of 125 666.8 cm^-1’ (Ref. 30(a)); Ref. 30(b): ‘Ogawa and Tanaka do not give an error limit for their measurements. The measured and calculated numbers in Table 1 of Ref. 30(a) differ typically by less than 0.5 cm^-1.’ Rydberg-series limit from absorption; the levels are not stated here.
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.