Meredith J. T. Jordan's research while affiliated with The University of Sydney and other places

... The energetics of reaction (5) have been further investigated using a number of electronic structure methods, as implemented in the Gaussian 16 program 56 . The BH&HLYP, M06-2X and B2PLYP-D3(BJ) density functional methods were considered: BH&HLYP was used in a previous investigation 38 and performs well for barrier heights for hydrogen abstraction reactions, although other properties may be less well reproduced with respect to higher levels of theory 57,58 , and both M06-2X and B2PLYP-D3 have been shown to be versatile and accurate for unimolecular reactions of small carbonyls [59][60][61] . Reaction (5) was also investigated using the MP2 and CCSD molecular orbital-based methods. ...

... We assigned the 1% quantum yield found by Harrison et al. (2019) for acetaldehyde to the selected aldehydes tested in GEOS-Chem, analogously to what was done for the box modelling (Section 2.1). The 1% from acetaldehyde 365 was taken as the reference quantum yield to test given that measurements for the rest of the aldehydes are not available, but the energy barriers for the production of H 2 from aldehyde photolysis indicates that the dissociation channels are accessible (Rowell et al., 2021). For acetaldehyde, glycolaldehyde, HPALD and RCHO, a branching ratio on the existing photolysis channels was added to account for the primary production of H 2 in addition to the existing photolysis products. ...

... The 1,5-H shift (Norrish type II process) occurred in the T 1 state and led to a triplet 1,4-biradical intermediate. Rowell et al. [21,22] studied 20 carbonyl compounds, among which 2-butenedial was not included. The photochemical process can occur in T 1 or S 1 states, depending on the reactants, namely on the S 1 energy threshold for the Norrish type II reaction. ...

... It is both directly emitted and formed as an oxidation product of volatile organic species. Several well-characterized photochemical processes follow absorption of light [7][8][9][10][11][12][13] . As a small molecule, HCHO is also a benchmark for high-level ab initio theory [14][15][16][17] . ...

... Some studies of the Norrish I reaction in small molecules showed that breaking the α C-C bond of ketones in excited states requires lower barriers than that in the ground state. However, the above studies did not consider the ultraviolet (UV) molar absorptivity of those excited states, so the possibility of excitation was not justified [31][32][33]. There have been few simulation studies of the photo-oxidative aging process of polymers. ...

... In recent years, evidence has emerged that H 2 is also a primary photolysis product of other carbonyls. Harrison et al. (2019) found that H 2 is directly produced from the photolysis of acetaldehyde with a quantum yield of 1 % at 1 atm and 298 K. Kharazmi (2018) found that longer carbonyls with β-H atoms, like propanal and methylpropanal, had even higher, though still modest, quantum yields of 3 % and 8 % respectively. These discoveries gave rise to the hypothesis that photolysis of all aldehydes might also directly yield H 2 . ...

... We further update the "base" GEOS-Chem mechanism with additional formic acid sources as described by Chen et al., 84 building on the prior work of Paulot et al. 5 and Millet et al. 39 These updates include phototautomerization of acetaldehyde, 85 oceanic emissions of alkene precurors to secondary formic acid, 5,39 agricultural and soil emissions of formic acid scaled to ammonia and nitrogen oxide uxes, 5 and uptake of formic acid on ice and dust. 5 We also include the newly implemented gasphase chemistry of DHI as described by Bates et al., 86 which incorporates DHI formation from isoprene hydroxynitrate hydrolysis, 87 and the reaction of isoprene hydroxyhydroperoxide with aqueous bisulte. ...

... reactants for the critical points on these PESs, compared to the reference values based on the prior theoretical calculations [72][73][74][75], ATcT thermochemical database [71], and the compendium of electronic energy levels of polyatomic transient molecules [76], are presented in Table 2. The PES obtained for the CO( Σ ) + H2 system in the present study largely coincided with those of previous studies [72][73][74][75]77]. ...

... It is both directly emitted and formed as an oxidation product of volatile organic species. Several well-characterized photochemical processes follow absorption of light [7][8][9][10][11][12][13] . As a small molecule, HCHO is also a benchmark for high-level ab initio theory [14][15][16][17] . ...

... 10,12 The involvement of a 1,4-biradical on the type-2 process was suggested, noting a significant decrease in yields of the products in the presence of a 1,4-biradical quencher like HBr, 12 but the effect of a triplet quencher such as 1,3-diene was relatively less significant. 11 Formations of long-lived intermediates like 2-propenol 13 and ethenone (ketene) were also evidenced in previous studies, and the significance of the type-2 pathway was demonstrated by measuring the photochemical quantum yields of the products. 12 The focus of the present study is the laboratory investigation of UV photooxidation of 2PN in the gas phase under a simulated tropospheric condition, which to our knowledge has not been reported till date. ...