Quantum yields for the photolysis of glyoxal below 350 nm and parameterisations for its photolysis rate in the troposphere

Salter, Robert J.; Blitz, Mark A.; Heard, Dwayne E.; Kovács, Tamás; Pilling, Michael J.; Rickard, Andrew R.; Seakins, Paul W.

doi:10.1039/c3cp43597k

Cited by 16 publications

(14 citation statements)

References 41 publications

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“…Above 395 nm, our zero pressure quantum yields are substantially higher than those of Chen and Zhu and Feierabend et al, (see Fig. 4 in the companion paper 4 ), because they did not carry out experiments at sufficiently low pressures to observe the non-linearity of the Stern-Volmer plots. Above 400 nm, the non-linearity of the Stern-Volmer plots, and the difficulty of making measurements at sufficiently low pressures to obtain an accurate intercept, make extrapolation to zero pressure more difficult and we have resorted to constraining the zero pressure yield to 2.0 at wavelengths above 400 nm, as discussed above.…”

Section: Zero Pressure Product Yields U 0hcocontrasting

confidence: 61%

“…Photodissociation to form HCO occurs out to wavelengths close to the thermodynamic limit. In the companion paper, 4 we determine photolysis quantum yields for l o 350 nm, and the rates of photolysis of glyoxal in the troposphere.…”

Section: Discussionmentioning

confidence: 99%

“…Under most conditions photolysis dominates, with a typical photolysis lifetime being 2-3 hours. 2,3 The companion paper 4 to this work discusses the atmospheric chemistry of glyoxal in greater detail; in this paper we focus on the detailed mechanism of glyoxal dissociation. In the region 200-450 nm, the thermodynamically (0 K) available product channels for the photolysis of glyoxal are: 2 (HCO) 2 + hn -2HCO l r 413 nm (P1a)…”

Section: Introductionmentioning

confidence: 99%

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Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Salter

Blitz

Heard

et al. 2013

Phys. Chem. Chem. Phys.

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The photolysis of glyoxal has been investigated in the 355-414 nm region by dye laser photolysis coupled with cavity ring-down spectroscopy. Absolute quantum yields of HCO, ΦHCO, were determined using the reaction of chlorine atoms with formaldehyde as an actinometer. The dependence of the quantum yield on pressure was investigated in 3-400 Torr of nitrogen buffer gas and at four temperatures: 233 K, 268 K, 298 K and 323 K. For 355 nm ≤ λ < 395 nm the HCO quantum yield is pressure dependent with linear Stern-Volmer (SV) plots (1/ΦHCO vs. pressure). The zero pressure quantum yield, obtained by extrapolation of the SV plots, rises from 1.6 to 2 between 355 and 382 nm and remains at 2 up to 395 nm. For λ ≥ 395 nm ΦHCO shows a stronger pressure dependence and non-linear SV plots, compatible with formation of HCO by dissociation from two electronic states of glyoxal with significantly different lifetimes. These observations are used to develop a mechanism for the photolysis of glyoxal over the wavelength range studied.

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Section: Zero Pressure Product Yields U 0hcocontrasting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Salter

Blitz

Heard

et al. 2013

Phys. Chem. Chem. Phys.

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“…Moreover, the SOA composition trend is well explained by a −CH 3 dilution effect. Previous studies on the different gas-phase (Forstner et al, 1997;Yu et al, 1997) and particle-phase (Hamilton et al, 2005;Sato et al, 2007Sato et al, , 2012 products support this methyl group dilution theory. A typical example is that more 3-methyl-2,5-furandione is observed in m-xylene than toluene and vice versa for 2,5furandione.…”

Section: Methyl Group Number Impact On Soa Formation Pathway From Monmentioning

confidence: 60%

Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NO<sub><i>x</i></sub> conditions

Tang

Nakao

et al. 2016

Atmos. Chem. Phys.

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Abstract. Substitution of methyl groups onto the aromatic ring determines the secondary organic aerosol (SOA) formation from the monocyclic aromatic hydrocarbon precursor (SOA yield and chemical composition). This study links the number of methyl groups on the aromatic ring to SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NOx conditions (HC/NO  >  10 ppbC : ppb). Monocyclic aromatic hydrocarbons with increasing numbers of methyl groups are systematically studied. SOA formation from pentamethylbenzene and hexamethylbenzene are reported for the first time. A decreasing SOA yield with increasing number of methyl groups is observed. Linear trends are found in both f44 vs. f43 and O / C vs. H / C for SOA from monocyclic aromatic hydrocarbons with zero to six methyl groups. An SOA oxidation state predictive method based on benzene is used to examine the effect of added methyl groups on aromatic oxidation under low-NOx conditions. Further, the impact of methyl group number on density and volatility of SOA from monocyclic aromatic hydrocarbons is explored. Finally, a mechanism for methyl group impact on SOA formation is suggested. Overall, this work suggests that, as more methyl groups are attached on the aromatic ring, SOA products from these monocyclic aromatic hydrocarbons become less oxidized per mass/carbon on the basis of SOA yield or chemical composition.

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“…Vertical simulations does not allow for adequate treatment of wavelength dependent photochemical processes, as we encounter e.g. photochemistry of heterocycles 16 , photolysis of glyoxal 17 , photoinitiating reactions 18 or chemistry of phytochromophores 19 (1)…”

Section: Introductionmentioning

confidence: 99%

On the importance of initial conditions for excited-state dynamics

et al. 2018

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Photodynamical simulations are increasingly used to explore photochemical mechanisms and interpret laser experiments. The vast majority of ab initio excited-state simulations are performed within semiclassical, trajectory-based approaches. Apart from underlying electronic-structure theory, the reliability of simulations is controlled by a selection of initial conditions for the classical trajectories. We discuss appropriate choices of initial conditions for simulations of different experimental arrangements: dynamics initiated by continuum-wave (CW) laser fields or triggered by ultrashort laser pulses. We introduce a new technique, CW-sampling, to treat the former case, based on the ideas of importance sampling, combined with the quantum thermostat approach based on the Generalized Langevin Equation (GLE) that allows for efficient sampling of both position and momentum space. The CW-sampling is particularly important for photodynamical processes initiated by absorption at the tail of the UV absorption spectrum. We also emphasize the importance of non-Condon effects for the dynamics. We demonstrate the performance of our approach on the photodissociation of the CF2Cl2 molecule (Freon CFC-12). A quantitative agreement with the experimental data is achieved with the use of empirical correlation energy correction (CEC) factor on top of FOMO-CASCI potential energy surfaces.

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Quantum yields for the photolysis of glyoxal below 350 nm and parameterisations for its photolysis rate in the troposphere

Cited by 16 publications

References 41 publications

Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NO<sub><i>x</i></sub> conditions

On the importance of initial conditions for excited-state dynamics

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Quantum yields for the photolysis of glyoxal below 350 nm and parameterisations for its photolysis rate in the troposphere

Cited by 16 publications

References 41 publications

Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Pressure and temperature dependent photolysis of glyoxal in the 355–414 nm region: evidence for dissociation from multiple states

Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NO&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; conditions

On the importance of initial conditions for excited-state dynamics

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Role of methyl group number on SOA formation from monocyclic aromatic hydrocarbons photooxidation under low-NO<sub><i>x</i></sub> conditions