Water Self-Diffusion in Glassy and Liquid Maltose Measured by Raman Microscopy and NMR

Zhu, Lei; Cai, Ting; Huang, Jun; Stringfellow, Thomas C.; Wall, Mark; Yu, Lian

doi:10.1021/jp202663r

Cited by 29 publications

(33 citation statements)

References 27 publications

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“…The breakdown of the SE relation for supercooled liquids and glasses is well known from the literature (Tarjus and Kivelson, 1995;Mendoza et al, 2015). This fact is also reported near the glass transition temperature for sugars (Champion et al, 1997;Rampp et al, 2000;Zhu et al, 2011;Power et al, 2013) and protein . All measurements indicate that the viscosity of SOA particles increases with decreasing relative humidity and that a semi-solid phase state is very likely achieved.…”

Section: Introductionmentioning

confidence: 55%

Kinetic modeling studies of SOA formation from α-pinene ozonolysis

et al. 2017

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Abstract. This paper describes the implementation of a kinetic gas-particle partitioning approach used for the simulation of secondary organic aerosol (SOA) formation within the SPectral Aerosol Cloud Chemistry Interaction Model (SPACCIM). The kinetic partitioning considers the diffusion of organic compounds into aerosol particles and the subsequent chemical reactions in the particle phase. The basic kinetic partitioning approach is modified by the implementation of chemical backward reaction of the solute within the particle phase as well as a composition-dependent particle-phase bulk diffusion coefficient. The adapted gasphase chemistry mechanism for α-pinene oxidation has been updated due to the recent findings related to the formation of highly oxidized multifunctional organic compounds (HOMs). Experimental results from a LEAK (Leipziger Aerosolkammer) chamber study for α-pinene ozonolysis were compared with the model results describing this reaction system.The performed model studies reveal that the particle-phase bulk diffusion coefficient and the particle-phase reactivity are key parameters for SOA formation. Using the same particlephase reactivity for both cases, we find that liquid particles with higher particle-phase bulk diffusion coefficients have 310 times more organic material formed in the particle phase compared to higher viscous semi-solid particles with lower particle-phase bulk diffusion coefficients. The model results demonstrate that, even with a moderate particle-phase reactivity, about 61 % of the modeled organic mass consists of reaction products that are formed in the liquid particles.This finding emphasizes the potential role of SOA processing. Moreover, the initial organic aerosol mass concentration and the particle radius are of minor importance for the process of SOA formation in liquid particles. A sensitivity study shows that a 22-fold increase in particle size merely leads to a SOA increase of less than 10 %.Due to two additional implementations, allowing backward reactions in the particle phase and considering a composition-dependent particle-phase bulk diffusion coefficient, the potential overprediction of the SOA mass with the basic kinetic approach is reduced by about 40 %. HOMs are an important compound group in the early stage of SOA formation because they contribute up to 65 % of the total SOA mass at this stage. HOMs also induce further SOA formation by providing an absorptive medium for SVOCs (semivolatile organic compounds). This process contributes about 27 % of the total organic mass. The model results are very similar to the LEAK chamber results. Overall, the sensitivity studies demonstrate that the particle reactivity and the particle-phase bulk diffusion require a better characterization in order to improve the current model implementations and to validate the assumptions made from the chamber simulations. The successful implementation and testing of the current kinetic gas-particle partitioning approach in a box model framework will allow further applications in a ...

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Section: Introductionmentioning

confidence: 55%

Kinetic modeling studies of SOA formation from α-pinene ozonolysis

et al. 2017

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“…The Stokes-Einstein relation is then sometimes used to estimate the diffusion coefficient. However, there is evidence to suggest that this hydrodynamic description is not generally applicable: the mobility of water and larger molecules deviate near the glass transition (Champion et al, 1997;Rampp et al, 2000;Zhu et al, 2011;Power et al, 2013). In addition, diffusion coefficients do not vary with temperature in the same way as viscosity at T g /T > 0.8 (Parker and Ring, 1995).…”

Section: H C Price Et Al: Quantifying Water Diffusion In High-viscmentioning

confidence: 99%

“…We have used a similar technique to Zhu et al (2011) to determine the diffusion coefficient of water in aqueous solutions. Zhu et al (2011) brought a H 2 O-maltose and a D 2 Omaltose droplet together until they touched, and used a Raman microscope to quantify diffusion between the droplets.…”

Section: H C Price Et Al: Quantifying Water Diffusion In High-viscmentioning

confidence: 99%

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Quantifying water diffusion in high-viscosity and glassy aqueous solutions using a Raman isotope tracer method

et al. 2014

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Abstract. Recent research suggests that under certain temperature and relative humidity conditions atmospheric aerosol may be present in the form of a glassy solid. In order to understand the impacts that this may have on aerosolcloud interactions and atmospheric chemistry, knowledge of water diffusion within such aerosol particles is required. Here, a method is described in which Raman spectroscopy is used to observe D 2 O diffusion in high-viscosity aqueous solutions, enabling a quantitative assessment of water diffusion coefficients, D water , as a function of relative humidity. Results for sucrose solutions compare well with literature data at 23.5 ± 0.3 • C, and demonstrate that water diffusion is slow (D water ∼ 5 × 10 −17 m 2 s −1 ), but not arrested, just below the glass transition at a water activity of 0.2. Room temperature water diffusion coefficients are also presented for aqueous levoglucosan and an aqueous mixture of raffinose, dicarboxylic acids and ammonium sulphate: at low humidity, diffusion is retarded but still occurs on millisecond to second timescales in atmospherically relevant-sized particles. The effect of gel formation on diffusion in magnesium sulfate solutions is shown to be markedly different from the gradual decrease in diffusion coefficients of highly viscous liquids. We show that using the Stokes-Einstein equation to determine diffusion timescales from viscosity leads to values which are more than 5 orders of magnitude too big, which emphasises the need to make measurements of diffusion coefficients. In addition, comparison of bounce fraction data for levoglucosan with measured diffusion data reveals that even when particles bounce the diffusion timescales for water are a fraction of a second for a 100 nm particle. This suggests a high bounce fraction does not necessarily indicate retarded water diffusion.

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“…Backward reactions describe the reaction from the aged organic particle-phase compounds to the original partitioned organic compounds that exchange directly with the gas phase. Organic aerosol-phase reactions can be irreversible reactions such as oxidation reactions or reversible reactions such as for instance dimerization/oligomerization (Hallquist et al, 2009;Ziemann and Atkinson, 2012). For the observed particle-phase dimerization, different possible reac- and (b) the transition between liquid and semi-solid (D b = 10 −14 m 2 s −1 ) aerosol particles and k c = 10 −4 s −1 .…”

Section: Representation Of Reversible Soa Formation Pathways and The mentioning

confidence: 99%

Modeling studies of SOA formation from α-pinene ozonolysis

Gatzsche

Iinuma

Tilgner

et al. 2017

Preprint

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Abstract. This paper describes the implementation of a kinetic gas-particle partitioning approach used for the simulation of secondary organic aerosol (SOA) formation within the SPectral Aerosol Cloud Chemistry Interaction Model (SPACCIM). The kinetic partitioning considers the diffusion of organic compounds into aerosol particles and the subsequent chemical reactions in the particle phase. The basic kinetic partitioning approach is modified by the implementation of chemical backward reaction of the solute within the particle phase as well as a composition dependent particle-phase bulk diffusion coefficient. The adapted gas-phase chemistry mechanism for &#945;-pinene oxidation has been updated due to the recent findings related to the formation of highly oxidized multifunctional organic compounds (HOMs). Experimental results from a LEAK (Leipziger Aerosolkammer) chamber study for &#945;-pinene ozonolysis were compared with the model results describing this reaction system. The performed model studies reveal that the particle-phase bulk diffusion coefficient and the particle phase reactivity are key parameters for SOA formation. Using the same particle phase reactivity for both cases we find that liquid particles with higher particle-phase bulk diffusion coefficients have 310-times more organic material formed in the particle phase compared to higher viscous semi-solid particles with lower particle-phase bulk diffusion coefficients. The model results demonstrate that, even with a moderate particle phase reactivity, about 61&#8201;% of the modeled organic mass consists of reaction products that are formed in the liquid particles. This finding emphasizes the potential role of SOA processing. Moreover, the initial organic aerosol mass concentration and the particle radius are of minor importance for the process of SOA formation in liquid particles. A sensitivity study shows that a 22-fold increase in particle size merely leads to a SOA increase of less than 10&#8201;%. Due to two additional implementations, allowing backward reactions in the particle phase and considering a composition dependent particle-phase bulk diffusion coefficient, the potential overprediction of the SOA mass with the basic kinetic approach is reduced by about 40&#8201;%. HOMs are an important compound group in the early stage of SOA formation because they contribute up to 65&#8201;% of the total SOA mass at this stage. HOMs also induce further SOA formation by providing an absorptive medium for SVOCs (semi-volatile organic compounds). This process contributes about 27&#8201;% of the total organic mass. The model results are very similar to the LEAK chamber results. Overall, the sensitivity studies demonstrate that the particle reactivity and the particle-phase bulk diffusion require a better characterization in order to improve the current model implementations and to validate the assumptions made from the chamber simulations. The successful implementation and testing of the current kinetic gas-particle partitioning approach in a box model framework will allow further applications in a 3D model for regional scale process investigations.

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Water Self-Diffusion in Glassy and Liquid Maltose Measured by Raman Microscopy and NMR

Cited by 29 publications

References 27 publications

Kinetic modeling studies of SOA formation from <i>α</i>-pinene ozonolysis

Kinetic modeling studies of SOA formation from <i>α</i>-pinene ozonolysis

Quantifying water diffusion in high-viscosity and glassy aqueous solutions using a Raman isotope tracer method

Modeling studies of SOA formation from α-pinene ozonolysis

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Water Self-Diffusion in Glassy and Liquid Maltose Measured by Raman Microscopy and NMR

Cited by 29 publications

References 27 publications

Kinetic modeling studies of SOA formation from &lt;i&gt;α&lt;/i&gt;-pinene ozonolysis

Kinetic modeling studies of SOA formation from &lt;i&gt;α&lt;/i&gt;-pinene ozonolysis

Quantifying water diffusion in high-viscosity and glassy aqueous solutions using a Raman isotope tracer method

Modeling studies of SOA formation from α-pinene ozonolysis

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Kinetic modeling studies of SOA formation from <i>α</i>-pinene ozonolysis

Kinetic modeling studies of SOA formation from <i>α</i>-pinene ozonolysis