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 `__ · :doc:`Catalogue ` · :doc:`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\. Register\: TC\-974\. **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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 ~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "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 :doc:`review register ` for the checks and decisions.