Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields

Emma L. D'Ambro; Kristian Holten Møller; Felipe D. Lopez-Hilfiker; Siegfried Schobesberger; Jiumeng Liu; John E. Shilling; Ben Hwan Lee; Henrik Grum Kjærgaard; Joel A. Thornton

doi:10.1021/acs.est.7b00460

Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields

Emma L. D'Ambro, Kristian Holten Møller, Felipe D. Lopez-Hilfiker, Siegfried Schobesberger, Jiumeng Liu, John E. Shilling, Ben Hwan Lee, Henrik Grum Kjærgaard, Joel A. Thornton^*

^*Corresponding author for this work

Department of Chemistry

34 Citations (Scopus)

Abstract

We report chamber measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation, in which radical concentrations were systematically varied and the molecular composition of semi- to low-volatility gases and SOA were measured online. Using a detailed chemical kinetics box model, we find that to explain the behavior of low-volatility products and SOA mass yields relative to input H₂O₂ concentrations, the second-generation dihydroxy hydroperoxy peroxy radical (C₅H₁₁O₆·) must undergo an intramolecular H-shift with a net forward rate constant of order 0.1 s^-1 or higher. This finding is consistent with quantum chemical calculations that suggest a net forward rate constant of 0.3-0.9 s^-1. Furthermore, these calculations suggest that the dominant product of this isomerization is a dihydroxy hydroperoxy epoxide (C₅H₁₀O₅), which is expected to have a saturation vapor pressure ∼2 orders of magnitude higher, as determined by group-contribution calculations, than the dihydroxy dihydroperoxide, ISOP(OOH)₂(C₅H₁₂O₆), a major product of the peroxy radical reacting with HO₂. These results provide strong constraints on the likely volatility distribution of isoprene oxidation products under atmospheric conditions and, thus, on the importance of nonreactive gas-particle partitioning of isoprene oxidation products as an SOA source.

Original language	English
Journal	Environmental Science and Technology
Volume	51
Issue number	9
Pages (from-to)	4978-4987
Number of pages	10
ISSN	0013-936X
DOIs	https://doi.org/10.1021/acs.est.7b00460
Publication status	Published - 2017

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D'Ambro, E. L., Møller, K. H., Lopez-Hilfiker, F. D., Schobesberger, S., Liu, J., Shilling, J. E., Lee, B. H., Kjærgaard, H. G., & Thornton, J. A. (2017). Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields. Environmental Science and Technology, 51(9), 4978-4987. https://doi.org/10.1021/acs.est.7b00460

Isomerization of Second-Generation Isoprene Peroxy Radicals : Epoxide Formation and Implications for Secondary Organic Aerosol Yields. / D'Ambro, Emma L.; Møller, Kristian Holten; Lopez-Hilfiker, Felipe D. et al.

In: Environmental Science and Technology, Vol. 51, No. 9, 2017, p. 4978-4987.

Research output: Contribution to journal › Journal article › Research › peer-review

D'Ambro, EL, Møller, KH, Lopez-Hilfiker, FD, Schobesberger, S, Liu, J, Shilling, JE, Lee, BH, Kjærgaard, HG & Thornton, JA 2017, 'Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields', Environmental Science and Technology, vol. 51, no. 9, pp. 4978-4987. https://doi.org/10.1021/acs.est.7b00460

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title = "Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields",

abstract = "We report chamber measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation, in which radical concentrations were systematically varied and the molecular composition of semi- to low-volatility gases and SOA were measured online. Using a detailed chemical kinetics box model, we find that to explain the behavior of low-volatility products and SOA mass yields relative to input H2O2 concentrations, the second-generation dihydroxy hydroperoxy peroxy radical (C5H11O6·) must undergo an intramolecular H-shift with a net forward rate constant of order 0.1 s-1 or higher. This finding is consistent with quantum chemical calculations that suggest a net forward rate constant of 0.3-0.9 s-1. Furthermore, these calculations suggest that the dominant product of this isomerization is a dihydroxy hydroperoxy epoxide (C5H10O5), which is expected to have a saturation vapor pressure ∼2 orders of magnitude higher, as determined by group-contribution calculations, than the dihydroxy dihydroperoxide, ISOP(OOH)2(C5H12O6), a major product of the peroxy radical reacting with HO2. These results provide strong constraints on the likely volatility distribution of isoprene oxidation products under atmospheric conditions and, thus, on the importance of nonreactive gas-particle partitioning of isoprene oxidation products as an SOA source.",

author = "D'Ambro, {Emma L.} and M{\o}ller, {Kristian Holten} and Lopez-Hilfiker, {Felipe D.} and Siegfried Schobesberger and Jiumeng Liu and Shilling, {John E.} and Lee, {Ben Hwan} and Kj{\ae}rgaard, {Henrik Grum} and Thornton, {Joel A.}",

year = "2017",

doi = "10.1021/acs.est.7b00460",

language = "English",

volume = "51",

pages = "4978--4987",

journal = "Environmental Science & Technology",

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T2 - Epoxide Formation and Implications for Secondary Organic Aerosol Yields

AU - D'Ambro, Emma L.

AU - Møller, Kristian Holten

AU - Lopez-Hilfiker, Felipe D.

AU - Schobesberger, Siegfried

AU - Liu, Jiumeng

AU - Shilling, John E.

AU - Lee, Ben Hwan

AU - Kjærgaard, Henrik Grum

AU - Thornton, Joel A.

PY - 2017

Y1 - 2017

N2 - We report chamber measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation, in which radical concentrations were systematically varied and the molecular composition of semi- to low-volatility gases and SOA were measured online. Using a detailed chemical kinetics box model, we find that to explain the behavior of low-volatility products and SOA mass yields relative to input H2O2 concentrations, the second-generation dihydroxy hydroperoxy peroxy radical (C5H11O6·) must undergo an intramolecular H-shift with a net forward rate constant of order 0.1 s-1 or higher. This finding is consistent with quantum chemical calculations that suggest a net forward rate constant of 0.3-0.9 s-1. Furthermore, these calculations suggest that the dominant product of this isomerization is a dihydroxy hydroperoxy epoxide (C5H10O5), which is expected to have a saturation vapor pressure ∼2 orders of magnitude higher, as determined by group-contribution calculations, than the dihydroxy dihydroperoxide, ISOP(OOH)2(C5H12O6), a major product of the peroxy radical reacting with HO2. These results provide strong constraints on the likely volatility distribution of isoprene oxidation products under atmospheric conditions and, thus, on the importance of nonreactive gas-particle partitioning of isoprene oxidation products as an SOA source.

AB - We report chamber measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation, in which radical concentrations were systematically varied and the molecular composition of semi- to low-volatility gases and SOA were measured online. Using a detailed chemical kinetics box model, we find that to explain the behavior of low-volatility products and SOA mass yields relative to input H2O2 concentrations, the second-generation dihydroxy hydroperoxy peroxy radical (C5H11O6·) must undergo an intramolecular H-shift with a net forward rate constant of order 0.1 s-1 or higher. This finding is consistent with quantum chemical calculations that suggest a net forward rate constant of 0.3-0.9 s-1. Furthermore, these calculations suggest that the dominant product of this isomerization is a dihydroxy hydroperoxy epoxide (C5H10O5), which is expected to have a saturation vapor pressure ∼2 orders of magnitude higher, as determined by group-contribution calculations, than the dihydroxy dihydroperoxide, ISOP(OOH)2(C5H12O6), a major product of the peroxy radical reacting with HO2. These results provide strong constraints on the likely volatility distribution of isoprene oxidation products under atmospheric conditions and, thus, on the importance of nonreactive gas-particle partitioning of isoprene oxidation products as an SOA source.

U2 - 10.1021/acs.est.7b00460

DO - 10.1021/acs.est.7b00460

M3 - Journal article

C2 - 28388039

AN - SCOPUS:85020748056

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JO - Environmental Science & Technology

JF - Environmental Science & Technology

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Isomerization of Second-Generation Isoprene Peroxy Radicals: Epoxide Formation and Implications for Secondary Organic Aerosol Yields

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