ravishankara_1986#

A. R. Ravishankara, P. H. Wine, C. A. Smith, P. E. Barbone and A. Torabi, “N2O5 photolysis: Quantum yields for NO3 and O(3P)”, J. Geophys. Res. 91, 5355 (1986)

Source record · Catalogue · Review register

DOI: 10.1029/jd091id05p05355

Source kind: measurement

Recorded technique: Pulsed laser photolysis at 298 K in N2. O(3P): resonance fluorescence (oxygen lamp, 131 nm, solar-blind photomultiplier, photon counting) after photolysis by an excimer or a Nd:YAG-dye laser at 248, 266, 286.9 and 288.9 nm, 75 torr N2 unless noted, each yield measured relative to O3 photolysis (O(3P) yield of O3 taken as one, O(1D) quenched by N2) just before and after; corrected for the absorption of the 131 nm radiation by N2O5 and, at 286.9 and 288.9 nm, for O(3P) from NO2 photolysis (2-15 %). NO3: 248 nm photolysis (spatially homogenised beam, fluence calibrated by O3 actinometry, ‘better than 8 %’), NO3 by multipass 662 nm laser absorption, 250-355 torr N2. N2O5 by UV absorption at 213.9 nm (Zn lamp), with a cross section of ‘4.00 x 10^-19 cm^2 [DeMore et al., 1983]’; sigma(N2O5) at 248 nm taken as 4.45 x 10^-19 cm^2 (pp. 5355-5358).

Materials in structured entries: N2O5

Dataset quantities: photodissociation_quantum_yield

Contents: 2 datasets; 0 formulas.

Curation notes#

Identity checked on the first page (PDF page 1 = journal p. 5355): Ravishankara, Wine, Smith, Barbone and Torabi, J. Geophys. Res. 91 (D5), 5355-5360 (1986). PDF page n = journal page 5354 + n. N2O5 only.

The yields depend on the cross sections assumed: the N2O5 density is measured at 213.9 nm and the photolysed fraction uses sigma(N2O5) at the photolysis wavelength (4.45 x 10^-19 cm^2 at 248 nm, 1.93 x 10^-19 at 266, 8.28 x 10^-20 at 286.9, 7.32 x 10^-20 at 288.9 nm; Table 1 footnote d), and the NO3 density uses NO3’s cross section at 662 nm (Ravishankara and Wine 1983; Marinelli et al. 1982). Doubt: the printed 213.9 nm cross section, 4.00 x 10^-19 cm^2 (p. 5355, page image checked), is smaller than the paper’s own 248 nm value, while N2O5’s spectrum falls monotonically from 208 to 398 nm (harwood_1998: 2.85 x 10^-18 at 214 nm, 4.19 x 10^-19 at 248 nm); it is probably a misprint for 4.00 x 10^-18 (an inference; TC-975). Harwood et al. (1998, p. 1316) re-evaluate the 248 nm NO3 yield with Yokelson et al.’s (1994) NO3 cross section as 0.77 +- 0.13 (2 sigma).

O(3P) (p. 5358): ‘Even though our systematic error for each Phi(O(3P)) is ~20 %, the relative values are much more precise’; the yield falls by a factor of about 4 from 248 to 290 nm. The authors postulate a channel N2O5 -> NO3 + NO + O(3P), threshold 298.5 nm at 298 K, beside NO3 + NO2 (p. 5359). Quoted (not taken): Margitan (1984) 0.35 +- 0.15 at 266 nm, Magnotta (1979) 0.35 +- 0.10 at 290-300 nm (O(3P)) and an upper limit of 0.1 for NO; Swanson et al. (1984) NO3 yields 0.89 +- 0.15 at 248 nm and 0.84 +- 0.09 at 350 nm. At very low helium pressure the NO3 yield was about 0.7, attributed to loss of excited NO3 before relaxation (p. 5358).

The laser wavelengths are nominal (248 nm KrF; 266 nm the fourth harmonic; 286.9 and 288.9 nm the dye laser), medium not stated.

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets#

ravishankara_1986/o3p_yield#

{
  "id": "o3p_yield",
  "material": "N2O5",
  "file": "N2O5/ravishankara_1986__o3p_yield.csv",
  "table": "tbl_92212005c108",
  "quantity": "photodissociation_quantum_yield",
  "abscissa_unit": "nm",
  "use": "primary",
  "parameters": {
    "product": "O(3P)",
    "temperature_k": 298.0
  },
  "uncertainty": {
    "column": true,
    "level": "not stated"
  }
}

Table 1 (p. 5356), last column ‘Phi +- Accuracy’: the O(3P) yield at 248, 266, 286.9 and 288.9 nm, 75 torr N2, 298 K. The accuracy includes the systematic error (~20 %, p. 5358); its level is not stated. The 266 nm value averages two sets of runs (0.36 +- 0.05 and 0.42 +- 0.06, 2 sigma; footnote g); the 286.9 and 288.9 nm values are corrected for O(3P) from NO2 (footnote h; uncorrected 0.21-0.28 and 0.16-0.19).

ravishankara_1986/no3_yield#

{
  "id": "no3_yield",
  "material": "N2O5",
  "file": "N2O5/ravishankara_1986__no3_yield.csv",
  "table": "tbl_eaa82cc4a2ec",
  "quantity": "photodissociation_quantum_yield",
  "abscissa_unit": "nm",
  "use": "primary",
  "parameters": {
    "product": "NO3 (ground state, detected at 662 nm after collisional relaxation)",
    "temperature_k": 298.0
  },
  "uncertainty": {
    "column": true,
    "level": "not stated"
  }
}

Table 2 (p. 5359), last cell, ‘(0.96 +- 0.13)^d’: ‘Uncorrected average. The error refers to a combination of random errors and systematic errors (8 % in F, 6 % in [N2O5], 6 % in sigma(N2O5), and 6 % in the absorption cross section of NO3 at 662 nm)’ (page image checked); level not stated. The same 0.96 +- 0.13 on p. 5358. 250-355 torr N2, 298 K. The random-only averages are 0.958 +- 0.060 (all runs) and 0.955 +- 0.064, 0.961 +- 0.062 (the two pressures), 2 sigma. Harwood et al.’s re-evaluation with a later NO3 cross section is 0.77 +- 0.13; harwood_1998 measured 0.64 +- 0.10 (TC-975).

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.