Reactions between small water-soluble carbonyl compounds, ammonium sulfate (AS), and/or amines were evaluated for their ability to form light-absorbing species in aqueous aerosol. Aerosol chemistry was simulated with bulk phase reactions at pH 4, 275 K, initial concentrations of 0.05 0.25 M, and UV-vis fluorescence spectroscopy monitoring. Glycolaldehyde-glycine mixtures produced the most intense absorbance. In compound AS, methylamine, or AS/glycine mixtures, product absorbance followed...

Reactions of methylglyoxal with amino acids, methylamine, and ammonium sulfate can take place in aqueous aerosol evaporating cloud droplets. These processes are simulated by drying droplets bulk solutions these compounds (at low millimolar 1 M concentrations, respectively) analyzing the residuals scanning mobility particle sizing, nuclear magnetic resonance, mass spectrometry (AMS), electrospray ionization MS. The results consistent imine (but not diimine) formation on a time scale seconds,...

Glyoxal, the simplest and most abundant α-dicarbonyl compound in atmosphere, is scavenged by clouds aerosol, where it reacts with nucleophiles to form low-volatility products. Here we examine reactions of glyoxal five amino acids common clouds. When glycine, serine, aspartic acid or ornithine are present at concentrations as low 30 μM evaporating aqueous droplets bulk solutions, 1,3-disubstituted imidazoles formed irreversible second-order detected nuclear magnetic resonance (NMR), aerosol...

Glyoxal and methyl glyoxal are common secondary atmospheric pollutants, formed from aromatic terpene precursors. Both compounds extremely water-soluble due to dihydrate formation partition into cloudwater. In this work, FTIR-ATR mass measurements indicate that both remain primarily in the condensed phase oligomer when aqueous solution droplets evaporated, regardless of concentration (≥1 mM) or, for glyoxal, droplet evaporation rate. FTIR spectral analyses suggest is triggered by conversion...

Glyoxal and methylglyoxal are scavenged by clouds, where a fraction of these compounds oxidized during the lifetime droplet. As cloud droplet evaporates, remaining glyoxal must either form low-volatility such as oligomers remain in aerosol phase, or transfer back to gas phase. A series experiments on evaporating aqueous droplets indicates that over atmospherically relevant concentration range for clouds fog (4−1000 μM), 33 ± 11% 19 13% remains phase while remainder evaporates. Measurements...

Glyoxal is a significant atmospheric aldehyde formed from both anthropogenic aromatic compounds and biogenic isoprene emissions. The chemical behavior of glyoxal relevant to secondary organic aerosol (SOA) formation analysis examined in GC−MS, electrospray ionization (ESI)-MS, particle chamber experiments. oligomers are shown rapidly decompose GC injection ports at temperatures ≥120 °C. dihydrate monomer dehydrated ≥140 °C during but shows only (n ≤ 7) upon ESI-MS analysis. Thus these...

Glyoxal reacts with methylamine in drying cloud droplet/aerosol surrogates to form high molecular mass oligomers along smaller amounts of 1,3 ‐dimethylimidazole and light‐absorbing compounds. The patterns observed by high‐resolution time‐of‐flight aerosol spectrometry indicate that from repeated imine units. reactions are 1st order each reactant: rate‐limiting formation is followed rapid dimer oligomer formation. While excess evaporates the droplet, half glyoxal does not, due...

Density functional theory (B3LYP//6-311+G*) calculations, including Poisson−Boltzmann implicit solvent and free energy corrections, are applied to study the hydration of methylglyoxal subsequent formation dimeric species in solution. Our calculations show that, unlike glyoxal, fully hydrated not thermodynamically favored over their less counterparts, nor dioxolane ring thermodynamic sink, which is agreement with experimental data. Instead, we find that aldol condensations most...

The effects of methylglyoxal uptake on the physical and optical properties aerosol containing amines or ammonium sulfate were determined before after cloud processing in a temperature- RH-controlled chamber. formation brown carbon was observed upon addition, detected as an increase water-soluble organic mass absorption coefficients below 370 nm drop single-scattering albedo at 450 nm. imaginary refractive index component k450 reached maximum value 0.03 ± 0.009 with aqueous glycine particles....

Reactions of carbonyl compounds in cloudwater produce organic aerosol mass through in-cloud oxidation and during postcloud evaporation. In this work, evaporation was simulated laboratory experiments on evaporating droplets that contain mixtures common atmospheric aldehydes with ammonium sulfate (AS), methylamine, or glycine. Aerosol diameters were measured monodisperse droplet drying polydisperse equilibration at 75% relative humidity, condensed-phase bulk thermogravimetric experiments. The...

Aqueous methylglyoxal chemistry has often been implicated as an important source of oligomers in atmospheric aerosol. Here we report on chemical analysis brown carbon aerosol particles collected from cloud cycling/photolysis chamber experiments, where gaseous and methylamine interacted with glycine, ammonium, or methylammonium sulfate seed particles. Eighteen N-containing were identified the particulate phase by liquid chromatography/diode array detection/electrospray ionization...

The reported optical, physical, and chemical properties of aqueous Maillard reaction mixtures small aldehydes (glyoxal, methylglyoxal, glycolaldehyde) with ammonium sulfate amines are compared those extracts ambient aerosol (water-soluble organic carbon, WSOC) the humic-like substances (HULIS) fraction WSOC. Using a combination new previously published measurements, we examine fluorescence, X-ray absorbance, UV/vis, IR spectra, complex refractive indices, 1H 13C NMR thermograms, electrospray...

The uptake of glyoxal by a variety organic and inorganic aerosol types was examined in Teflon chamber. Rapid observed for all liquid-phase aerosols at relative humidity levels tested (<5 to 50% RH). Even with known water content, Henry's Law cannot predict uptake: H* > (3 ± 1.5) × 108 mol kg−1 atm−1 l-tartaric acid, (1 0.5) dl-malic acid = (2 1) 107 malonic aerosol. Other particles containing amine functional groups (arginine, aspartic glutamic acid) took up even more (H* 3 108). trend...

In aqueous solution, aldehydes, and to a lesser extent ketones, hydrate form geminal diols. We investigate the hydration of methylglyoxal (MG) in gas phase, process not previously considered occur water-restricted environments. this study, we spectroscopically identified diol (MGD) obtained gas-phase partial pressures MG MGD. These results, conjunction with relative humidity, were used obtain equilibrium constant, K P , for water-mediated phase. The Gibbs free energy process, Δ G ° as...

Density functional theory calculations, including Poisson−Boltzmann implicit solvent and free energy corrections, are applied to study the mechanism of experimentally observed imidazole formation from reaction glyoxal methylamine in solution. Our calculations suggest that a diimine species is an important intermediate reaction. Under acidic conditions, we find acts as nucleophile attacking carbonyl group either formaldehyde or first generate acyclic enol intermediate, which then goes on...

Secondary organic aerosol makes up a significant fraction of the total mass, and growing body evidence indicates that reactions in atmospheric aqueous phase are important contributors to formation can help explain observations cannot be accounted for using traditional gas-phase chemistry. In particular, between small molecules have been proposed as source light absorbing compounds observed numerous locations. Past work has established α-dicarbonyls amines evaporating water droplets produces...

In this study, we have explored the phase behavior and ice nucleation properties of secondary organic aerosol made from aqueous processing (aqSOA). AqSOA was dark reactions methylglyoxal with methylamine in simulated evaporated cloud droplets. The resulting particles were probed 215 to 250 K using Raman spectroscopy coupled an environmental cell. We find these are a semisolid or glassy state based upon their when exposed mechanical pressure as well flow behavior. Further, that aqSOA poor...

Halogen atoms, particularly chlorine are well known to be highly reactive and play a central role in the chemistry of upper atmosphere. A large potential source these halogens lower atmosphere (troposphere) exists form sea salt particles. variety laboratory, field modelling studies strongly suggests that there heterogeneous reactions particles which generate photochemically active halogen species such as Cl marine areas. In addition, is increasing evidence for contribution bromine atoms...

Density functional theory (B3LYP//6-311+G*) calculations including Poisson−Boltzmann implicit solvent were used to study the hydration of glyoxal and subsequent formation dimeric species in solution. Our show that dioxolane ring dimer is thermodynamic sink among all monomers dimers with varying degrees hydration. Although fully hydrated are thermodynamically favored over their less counterparts, we find a preliminary dehydration step precedes dimerization closure. Ring closure open...

A computational protocol utilizing density functional theory calculations, including Poisson-Boltzmann implicit solvent and free energy corrections, is applied to study the thermodynamic kinetic landscape of glycolaldehyde in solution. Comparison made NMR measurements dissolved glycolaldehyde, where initial dimeric ring structure interconverts among several species before reaching equilibrium hydrated monomer dominant. There good agreement between computation experiment for concentrations...

Formaldehyde and acetaldehyde are commonly found in cloud droplets because of reversible partitioning hydration reactions. An SOA formation pathway was recently identified which these common aldehydes irreversibly incorporated into imidazole derivatives formed by reaction with dicarbonyl species ammonium salts or amine species. Here we use ultraviolet–visible nuclear magnetic resonance kinetic measurements to determine the influence formaldehyde on aqueous methylglyoxal chemistry. The...

Methylamine, a common atmospheric amine species, is found in the gas, particle, and aqueous phases. It has been shown to form light-absorbing, oligomeric species reactions with methylglyoxal other aldehyde bulk aqueous-phase experiments when mixed into seed aerosol as sulfate salt. Here, we explore influence of multiphase methylamine chemistry on production, properties, molecular composition. When particles were exposed ∼2 ppm gas humid chamber, rapid browning was observed, but not growth....

Glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone form N-containing oligomeric compounds during simulated cloud processing with small amines. Using a novel hygroscopicity tandem differential mobility analysis (HTDMA) system that allows varied humidification times, the hygroscopic growth (HG) of each resulting products was measured. Continuous water uptake (gradual deliquescence) observed beginning at ∼40% RH for all aldehyde-methylamine products. Particles containing ionic reaction...

In order to predict the amount of secondary organic aerosol formed by heterogeneous processing methylglyoxal, uptake coefficients (γ) and estimates reversibility are needed. Here, extracted from chamber studies involving ammonium sulfate glycine seed at high relative humidity (RH ≥ 72%). Methylglyoxal on prereacted particles had a strong dependence RH, increasing γ = 0.4 × 10–3 5.7 between 72 99% RH. Continuous methylglyoxal losses were also observed in presence aqueous 95% RH (γAS,wet 3.7 ±...