harwood_1998#

M. H. Harwood, J. B. Burkholder and A. R. Ravishankara, “Photodissociation of BrONO2 and N2O5: Quantum Yields for NO3 Production at 248, 308, and 352.5 nm”, J. Phys. Chem. A 102, 1309 (1998)

Source record · Catalogue · Review register

DOI: 10.1021/jp9729829

Source kind: measurement

Recorded technique: Pulsed excimer-laser photolysis (KrF 248, XeCl 308, XeF 352.5 nm) in a 100 cm, 0.9 cm bore flow cell at about 298 K, in 150-600 Torr of N2 or O2; NO3 detected by absorption of a tunable diode laser at its 661.9 nm peak; photolyte concentrations by UV absorption (D2 lamp, 270 mm spectrograph with a 1024-element diode array, about 1 nm FWHM, 210-350 nm; wavelength scales calibrated with a mercury pen-ray lamp). The NO3 quantum yield of N2O5 measured against actinometers: HNO3 photolysis (248 nm), F2/HNO3 (all three), O3 photolysis (308 nm) and O3/Cl2 (352.5 nm). N2O5 made from O3 + NO2 and stored at 195 K; HNO3 impurity below 1 % (chemical-ionisation mass spectrometry; pp. 1309-1312).

Materials in structured entries: N2O5

Dataset quantities: absorption_cross_section, photodissociation_quantum_yield

Contents: 3 datasets; 0 formulas.

Curation notes#

Identity checked on the first page (PDF page 1 = journal p. 1309): Harwood, Burkholder and Ravishankara, J. Phys. Chem. A 102, 1309-1317 (1998). PDF page n = journal page 1308 + n. Curated for N2O5 only; the BrONO2 yields (0.28 +- 0.09, 1.01 +- 0.35, 0.92 +- 0.43 at 248, 308, 352.5 nm; Table 4) and the Br and Cl + BrONO2 rate coefficients (Table 5) are not taken (BrONO2 and its reactions are not registered).

N2O5 NO3 QUANTUM YIELD (abstract, p. 1309): ‘0.64 +- 0.10, 0.96 +- 0.15, and 1.03 (+-) 0.15 at 248, 308, and 352.5 nm, respectively’; ‘All quoted uncertainties are 2 sigma and include estimated systematic errors’. Table 3’s note: the method values’ uncertainties are ‘2 sigma of the measurement precision. The absolute uncertainties (2 sigma) including estimated errors are +-15 % of the measured value’ (the extraction’s ‘(15%’ is the +-, image checked). Doubts: (1) p. 1316 gives the 248 nm value as ‘0.64 +- 0.20 (2 sigma)’, twice the abstract’s +-0.10; 15 % of 0.64 is 0.10. (2) The 352.5 nm average 1.03 does not follow from Table 3’s two methods (0.91 +- 0.04 and 1.21 +- 0.04, whose mean is 1.06); 248 nm (0.67 +- 0.14, 0.64 +- 0.08; weighted mean 0.65) and 308 nm (0.88, 1.03; mean 0.955) do. The paper does not say how the averages were formed. The values used for the BrONO2 analysis were 0.64, 1.0 and 1.0 (Table 3).

COMPARISONS (p. 1316): at 248 nm ‘compares well with 0.77 +- 0.13 (2 sigma) measured by Ravishankara et al. [ravishankara_1986] at 248 nm and 0.80 by Burrows et al. at 254 nm’, both corrected by the authors to the NO3 cross section of Yokelson et al. (1994) used here; Ravishankara et al. printed 0.96 +- 0.13 (TC-975). At 350 nm Swanson et al. (1984) ‘close to unity’. Ravishankara et al.’s O(3P) yield at 248 nm, 0.72 +- 0.17, is ‘approximately equal’ to the NO3 yield; a yield below one implies other products (NO2*, NO + O).

CROSS SECTIONS (Table 2, p. 1312): measured with the diode array, ‘normalized to the value reported by Harwood et al. [J. Photochem. Photobiol. A 73, 167 (1993)] at 280 nm’; agrees with that paper within 3 % over the whole overlap and with DeMore et al.’s recommendation above 260 nm, systematically lower below 260 nm (attributed to HNO3 in earlier samples). Temperature about 298 K (the cell temperature, p. 1310). No uncertainty is stated for the cross sections. Wavelengths: the medium is not stated; the scale was calibrated with mercury lines (usually air values), so standard air is recorded; the difference, 0.07 nm, is far below the 1 nm resolution and the 2 nm grid. Table 1 (p. 1310) lists ‘this work’ N2O5 cross sections used in the analysis: 41.9 (248 nm) and 2.40 (308 nm), as Table 2, but 1.89 x 10^-20 cm^2 at 352.5 nm, ten times Table 2’s 0.188 (352 nm) and 0.177 (354 nm), and equal to Table 2’s 312 nm value (1.90) within rounding: a misprint in Table 1 (the BrONO2 yields, ratios to N2O5, would be ten times smaller with it). Table 1 is not extracted.

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

Datasets#

harwood_1998/cross_section#

{
  "id": "cross_section",
  "material": "N2O5",
  "file": "N2O5/harwood_1998__cross_section.csv",
  "table": "tbl_52089e995460",
  "quantity": "absorption_cross_section",
  "unit": "cm2",
  "scale": 1e-20,
  "abscissa_unit": "nm",
  "wavelength_medium": "standard_air",
  "use": "primary",
  "parameters": {
    "temperature_k": 298.0
  }
}

Table 2 (p. 1312), 96 wavelengths 208-398 nm every 2 nm, 10^-20 cm^2 molecule^-1 (footnote a). The absolute scale is Harwood et al. (1993)’s at 280 nm (record notes). Uncertainty not stated.

harwood_1998/no3_yield#

{
  "id": "no3_yield",
  "material": "N2O5",
  "table": "text",
  "quantity": "photodissociation_quantum_yield",
  "abscissa_unit": "nm",
  "use": "primary",
  "parameters": {
    "product": "NO3 (ground state, detected at 661.9 nm after collisional relaxation)",
    "temperature_k": 298.0
  },
  "uncertainty": {
    "column": true,
    "level": "2 sigma"
  }
}

3 inline points in the source record.

Abstract (p. 1309) and p. 1316: the NO3 quantum yield of N2O5 photolysis, independent of pressure (150-600 Torr N2 or O2 bath gas, about 298 K), 2 sigma including estimated systematic errors. Excimer-laser lines at their nominal wavelengths. p. 1316 prints +-0.20 at 248 nm (record notes). Disagrees with ravishankara_1986/no3_yield at 248 nm (TC-975).

harwood_1998/no3_yield_by_method#

{
  "id": "no3_yield_by_method",
  "material": "N2O5",
  "file": "N2O5/harwood_1998__no3_yield_by_method.csv",
  "table": "tbl_952e9553cc98",
  "quantity": "photodissociation_quantum_yield",
  "abscissa_unit": "nm",
  "use": "check",
  "parameters": {
    "product": "NO3 (ground state, detected at 661.9 nm after collisional relaxation)",
    "temperature_k": 298.0
  },
  "uncertainty": {
    "column": true,
    "level": "2 sigma"
  }
}

Table 3 (p. 1313): the NO3 yield by actinometric method (row id: method and wavelength), +- 2 sigma of the measurement precision only (the systematic +-15 % excluded). The averages are no3_yield.

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.