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J Phys Chem A

Title:		"Isoprene-Derived Organosulfates: Vibrational Mode Analysis by Raman Spectroscopy, Acidity-Dependent Spectral Modes, and Observation in Individual Atmospheric Particles"
Author(s):		Bondy AL; Craig RL; Zhang Z; Gold A; Surratt JD; Ault AP;
Address:		"Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109 United States. Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States. Department of Environmental Health Sciences, University of Michigan , Ann Arbor, Michigan 48109, United States"
Journal Title:		J Phys Chem A
Year:		2018
Volume:		20171227
Issue:		1
Page Number:		303 - 315
DOI:		10.1021/acs.jpca.7b10587
ISSN/ISBN:		1520-5215 (Electronic) 1089-5639 (Linking)
Abstract:		"Isoprene, the most abundant biogenic volatile organic compound (BVOC) in the atmosphere, and its low-volatility oxidation products lead to secondary organic aerosol (SOA) formation. Isoprene-derived organosulfates formed from reactions of isoprene oxidation products with sulfate in the particle phase are a significant component of SOA and can hydrolyze forming polyols. Despite characterization by mass spectrometry, their basic structural and spectroscopic properties remain poorly understood. Herein, Raman microspectroscopy and density functional theory (DFT) calculations (CAM-B3LYP level of theory) were combined to analyze the vibrational modes of key organosulfates, 3-methyltetrol sulfate esters (racemic mixture of two isomers), and racemic 2-methylglyceric acid sulfate ester, and hydrolysis products, 2-methyltetrols, and 2-methylglyceric acid. Two intense vibrational modes were identified, nu(RO-SO(3)) (846 +/- 4 cm(-1)) and nu(s)(SO(3)) (1065 +/- 2 cm(-1)), along with a lower intensity delta(SO(3)) mode (586 +/- 2 cm(-1)). For 2-methylglyceric acid and its sulfate esters, deprotonation of the carboxylic acid at pH values above the pK(a) decreased the carbonyl stretch frequency (1724 cm(-1)), while carboxylate modes grew in for nu(s)(COO(-)) and nu(a)(COO(-)) at 1413 and 1594 cm(-1), respectively. The nu(RO-SO(3)) and nu(s)(SO(3)) modes were observed in individual atmospheric particles and can be used in future studies of complex SOA mixtures to distinguish organosulfates from inorganic sulfate or hydrolysis products"
Keywords:
Notes:		"PubMed-not-MEDLINEBondy, Amy L Craig, Rebecca L Zhang, Zhenfa Gold, Avram Surratt, Jason D Ault, Andrew P eng 2017/12/09 J Phys Chem A. 2018 Jan 11; 122(1):303-315. doi: 10.1021/acs.jpca.7b10587. Epub 2017 Dec 27"