Near Infrared Photochemistry of Pyruvic Acid in Aqueous Solution

Larsen, Molly C.; Vaida, Veronica

doi:10.1021/jp2087972

Cited by 44 publications

(48 citation statements)

References 107 publications

(245 reference statements)

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“…Under typical atmospheric conditions, aqueous photolysis is not likely to be a significant atmospheric sink of the relatively simple carbonyls investigated in this manuscript. There are important exceptions to this rule including pyruvic acid and acetoacetic acid; we note that aqueous photolysis experiments of pyruvic acid are well established in the literature (Leermakers and Vesley, 1963;Larsen and Vaida, 2012;Guzmán et al, 2006;Guzmán et al, 2007). While carbonyls, keto-carboxylic acids, and hydroxyl-carbonyls may readily partition into cloud and fog droplets, once in the aqueous phase, oxidation by dissolved OH is a more efficient removal process than direct photolysis.…”

Section: Atmospheric Implicationsmentioning

confidence: 82%

Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

Epstein¹,

Tapavicza²,

Furche³

et al. 2013

Preprint

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Gas phase photolysis is an important tropospheric sink for many carbonyl compounds, however the significance of direct photolysis of carbonyl compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived Henry's law parameters, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will not have competitive aqueous photolysis rates. We also present molecular dynamics simulations of atmospherically relevant carbonyl compounds designed to estimate gas and aqueous phase extinction coefficients. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only three out of the 92 carbonyl compounds investigated, pyruvic acid, 3-oxobutanoic acid, and 3-oxopropanoic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α, β conjugation, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected

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Section: Atmospheric Implicationsmentioning

confidence: 82%

Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

Epstein¹,

Tapavicza²,

Furche³

et al. 2013

Preprint

View full text Add to dashboard Cite

show abstract

“…The aqueous chemistry of pyruvic acid is generally defined by the formation of oligomeric species, under both light and dark conditions. The aqueous phase photochemistry of pyruvic acid has been studied previously in the literature 41,[43][44][45]56,60,61 and is known to generate a surprisingly complex mixture of observed photoproducts, many of which have been assigned following the literature mechanism.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

et al. 2017

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The aqueous phase photochemistry of pyruvic acid, an important oxidation product of isoprene, is known to generate larger oligomeric species that may contribute to the formation of secondary organic aerosol in the atmosphere. Using high resolution negative mode electrospray ionization mass spectrometry, the aqueous photochemistry of dilute solutions of pyruvic acid (10, 1, and 0.5 mM) under anaerobic conditions was investigated. Even at the lowest concentration, covalently bonded dimers and trimers of pyruvic acid were observed as photochemical products. We calculate that it is energetically possible to photochemically generate parapyruvic acid, a dimer of pyruvic acid that is known to form via dark oligomerization processes. Subsequent photochemical reactions of parapyruvic acid with pyruvic acid form larger oligomeric products, such as 2,4-dihydroxy-2-methyl-5-oxohexanoic acid. A robust and relatively simple photochemical mechanism is discussed that explains both the conditional dependence and wide array of products that are observed.

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“…URL: http://www.esmedvedev.orc.ru. omy and astrophysics (Najita et al, 2009;Rothman et al, 2010), overtone-induced chemistry (Crim, 1984(Crim, , 1990(Crim, , 1996Gupta et al, 2010;Hutchinson, 1986;Larsen and Vaida, 2012;Scherer and Zewail, 1987;Takahashi et al, 2008), in studies of intramolecular processes (Fleming et al, 1991;Hippler and Quack, 1996;Portnov et al, 2012), and nonradiative transitions in laser crystals and glasses (Sveshnikova and Ermolaev, 2011).…”

Section: Introductionmentioning

confidence: 99%

Towards understanding the nature of the intensities of overtone vibrational transitions

Medvedev

2012

The Journal of Chemical Physics

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The overtone vibrational transitions, i.e., transitions between states separated by more than one vibrational quantum play important role in many fields of physics and chemistry. The overtone transition is a purely quantum process associated with the so-called dynamical tunneling [Heller, E. J., "The many faces of tunneling," J. Phys. Chem. A 103(49), 10433-10444 (1999)] whose probability is small as compared to the fundamental transition. The transition probability is proportional to the Landau-Lifshitz tunneling factor similar to the Gamov factor in nuclear physics. However, as opposed to the Gamov tunneling, the Landau-Lifshitz tunneling lacks any barrier to tunnel through: Its probability looks as if the system were forced to "dive" under the barrier up to a point where the transition can be performed without any change in momentum, hence with a high probability, and then to "emerge back" in a new state. It follows that the transition probability is associated with the shape of the potential in the classically forbidden region in the same sense as the transition energy is associated with the shape of the potential in the classically allowed region, as implied by the Bohr-Sommerfeld quantization rule, and in the same sense as the probability of the Gamov tunneling is associated with the shape of the potential within the barrier region. As soon as the tunneling character of the transition is recognized, the well-known extreme sensitivity of the overtone intensities to small variations of the fitting function representing the molecular potential [Lehmann, K. K. and Smith, A. M., "Where does overtone intensity come from?" J. Chem. Phys. 93(9), 6140-6147 (1990)] becomes fully understood: Small variations of the potential in the classical region, which do not affect the energy levels significantly, cause large variations in the forbidden region and hence do affect the tunneling factor. This dictates a clear strategy of constructing the potential energy and dipole moment functions (PEF and DMF) capable of explaining the data of vibrational spectroscopy and possessing a predictive power. In this paper, we will show that, for stretching vibrations, knowledge of the inner wall of the PEF is necessary to perform this task. Incorrect behavior of the PEF at extremely small interatomic separations corresponding to energies well above the dissociation limit results in an incorrect rate of the intensity falloff, hence a rapid increase of discrepancies between the calculated and observed intensities with overtone number. Analysis of experimental data on some di- and polyatomic molecules and their interpretations is presented, which shows that neglecting the tunneling nature of overtone transitions does not permit making predictions of the intensities with a known uncertainty. A new approach has to be developed. First of all, an ab initio PEF giving correct energy levels and having correct behavior of the repulsive wall must be constructed; thereafter, an ab initio DMF is invoked to explain the experimental data for lower (obs...

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Near Infrared Photochemistry of Pyruvic Acid in Aqueous Solution

Cited by 44 publications

References 107 publications

Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets

Mechanistic Description of Photochemical Oligomer Formation from Aqueous Pyruvic Acid

Towards understanding the nature of the intensities of overtone vibrational transitions

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